No one mentioned Xmarks (almost all browsers) to sync bookmarks and tabs between browsers

OneNumber (chrome) which checks for Gmail, GReader, GVoice and wave for updates.

Then I would recommend Boomerang for Gmail (both FF and Chrome) that allows you to postpone an email to send to whenever you want.

Google Dictionary (chrome): double click a word and it shows you the definition - really unobtrusive

Lazarus:Form recovery (chrome) - if you were typing some text in a textArea/field and the browser crashes it can easily put the text back in when you open the page again.

Rapportive for Gmail (chrome, but i thinks it also works in FF) - shows you details about senders, social networking accounts, etc

Stop Autoplay for Youtube (chrome) - great if you like to open many videos in tabs and dont want to hear them play all at the same time

Chrome: JSONView & XML Tree are awesome. I also use Rapportive w/ Gmail.

Firefox: Firebug, YSlow & Web Developer toolbar for development. I also use ForecastFox for weather and occasionally S3Fox to check something on S3.

Adblock - After using it for a while, it becomes impossible to NOT use it, and still retain focus. Every page contains something that is fighting for your attention when it's not in use.

Firebug - Incredible client-side development tool.

Show anchors - Reveals anchors (<a> tag) in the page, making it easy to make more precise links into pages.

Tamper data - Makes it possible to modify browser requests before submitting them to the server. Great addition to Firebug as a development tool.

I used to have a lot more extensions installed on Firefox, but right now all I actually use is:

AdBlock Plus, Download Statusbar, and Tab Scope.

Although one personal 'hack' almost counts: I moved the bookmark toolbar up next to the system menu, to use up all that space and give me quick access to all the sites I read. I have about 14 folders up there, and the Readability bookmarklet. I'm nervous about FF4 because I don't know where I'll be able to put my bookmarks...

Chromium:

Adblock + Browser Button for Adblock (obvious...)

Chromium Wheel Smooth Scroller (similar to iPhone kinetic scrolling)

Google Mail Checker Plus (obvious)

Instachrome (integration with Instapaper)

iReader (similar to Safari Reader)

Pinboard Tools (integration with Pinboard bookmarks service)

Reader Plus (changes the default theme of Google Reader among other customizations)

Redgur (shows all imgur stored images present on a page)

RSS Subscription Extension (obvious)

Search Preview for Google (website previews on search results)

Send using Gmail (mail_to integration with Gmail)

Stylish (similar to Greasemonkey but for CSS styling)

Adblock

builtwith - tries to tell you what tech sites use under the hood

delicious bookmarkts - official

docs PDF/powerpoint viewer - opens PDF links with google docs viewer instead of adobe

eye dropper

goo.gl url shortener

gmail checker plus

ireader - reading format

lastpass

linkpush - saves link for opening on android (has an app on anroid you open to get that link)

measureit! - measure pixels between stuff

rss subscription extension - adds fireefox like detection for RSS feeeds

stayfocusd - 30 mins of HN/facebook etc a day

I use several Firefox addons, most of them have been already mentioned. However, one of my favourite addons has not been mentioned:

Quieturl

This addon transforms urls that are plain text into clickable anchors. Very very handy, I couldn't browse without it now.

AdThwart (never fails) : https://chrome.google.com/extensions/detail/cfhdojbkjhnklbpk...

AutoPagerize (awesome) : https://chrome.google.com/extensions/detail/igiofjhpmpihnifd...

Google Translate (v handy) : https://chrome.google.com/extensions/detail/aapbdbdomjkkjkao...

Shareaholic (mainly for the instant short goo.gl urls) : https://chrome.google.com/extensions/detail/aapbdbdomjkkjkao...

Smooth Gestures (speeds things up) : https://chrome.google.com/extensions/detail/lfkgmnnajiljnolc...

Smooth Scroll (easier on the eyes) : https://chrome.google.com/extensions/detail/cccpiddacjljmfbb...

These could all come standard in my view and most people would appreciate it.

Chrome (main browser) Extensions:

* AdBlock

* Firebug Lite for Google Chrome

* Minimalistic Google Reader

* RSS Subscription Extension (by Google)

--

Firefox (for development, where some extensions in Chrome aren't available) Add-Ons:

* Firebug

* JSONView

* Live HTTP Headers

* Modify Headers

* Page Speed

* User Agent Switcher

* Web Developer Toolbar

* YSlow

--

I also have a folder of bookmarklets on my toolbar in Chrome:

* Google Analytics: Last Week

* Huffduffer: Add

* Instapaper: Add

* Pinboard: Add

* Twitter: Remove @mentions

* Readability

* Inject jQuery

I forget what it is called, and am on my mobile now, but I use one which loads the next paginated page below the one you are viewing, so hacker news becomes one long page for me. only loads the next age when you get down the page. love it.

also one to tweet the page I am viewing. I use twitter as more of an annotated favorites/bookmark list than anything else: twitter.com/liamjford

I think I'm the only person that doesn't use adblock.

Anyways on chrome: ireader, google reader "note in reader", hckr news (never noticed what it does though), and delicious. Using the dev channel build of chrome.

On FF: Treeview, someone on hn suggested it to me and I'm really hoping something similar comes to chrome. I'd use firefox more but still experience it memory leaking/crashing too much.

Firefox:

Wappalyzer http://wappalyzer.com

Adlock Plus http://adblockplus.org/en/

Flashblock http://flashblock.mozdev.org/

NoScript http://noscript.net/

Firebug http://getfirebug.com/

Firefox: - Firebug (my life wouldn't be same (or sane) without it) - Remove cookies for site (one click to remove all cookies for current domain, essential when developing cookie based sites) - FireGestures (lets you go back, reload, close tabs, etc. by preconfigured right click gestures - a feature invented by Opera I believe, I can't browse without it) - AdBlockPlus (I hate to admit this but a news site I visit frequently is so loaded with flash ads that my machine almost becomes unresponsive upon visiting)

Chrome: I try to find the same extensions as for Firefox but: - Firebug lite was missing the "Net" panel last time I checked - I haven't found a gestures addon that doesn't suck - I haven't found a remove cookies for site add-on

So migrating to Chrome has been quite hard for me.

PS. Yes, I'm a web developer

Firefox: Adblock, Flashblock, Leechblock, Firefox Sync, Tab Kit, Copy Plain Text.

Edit: oh, also Readability.

NoScript, possibly the best thing about FF.

Firebug, pretty handy.

Tamper Data, for viewing HTTP headers and tampering with them.

ShowIP, shows the current website's IP.

leetkey, great for text transformations, various encoders/decoders.

Screengrab, for taking screenshots.

Scrapbook Plus, for archiving pages (can also do some light crawling with it)

Mozilla Archive Format, also for archiving pages.

Delicious Bookmarks, for bookmarks.

AppTab, to make tabs sticky.

OptimizeGoogle, to make Google searching better.

UnPlug, for downloading embedded content.

DownThemAll, for downloading things.

HTTPS-Everywhere, redirects to HTTPS versions of certain websites.

ErrorZilla Plus, makes error pages more useful.

Those are the best ones, I use various other extensions depending on what I'm doing. I have a few addons deactivated at any given time.

Firefox:

Web Developer Toolbar, Firebug, DownThemAll!, ColorZilla

Frankly, all I ever use Firefox for anymore is testing/development and big or multifile downloads (DownThemAll! is kind enough to autosuspend and resume with the often wonky wifi I'm usually connected to).

Chrome:

Web Developer Toolbar, Readability, Flash Blocker

The version of the Web Developer Toolbar for Chrome is extremely limited, but it fills a few holes in the built-in developer tools. I'd love to have a download manager comparable to DownThemAll! for Firefox, but the Chrome API prevents most of the features I like from being implemented. Oh, well.

I don't use Chrome (privacy issues), but for Firefox,

* Flashblock

* Greasemonkey

* Firebug

* It'sAllText (which allows the use of an external editor)

* A few mostly inconsequential ones, like IdentFavicon, etc.

I find that flashblock takes care of most of my ad-blocking needs, and the rest I can do with a local DNS server. The re-emergence of badly behaved Javascript (Remember when all we had to worry about was scrolling/blinking text and alert() boxes? Those were the days.) is what prompted me to install Greasemonkey; I've got a little script that wipes iframes and kills window.XMLHttpRequest, for example

I have a lot, but Ultimate Chrome Flag is my favorite.

The reason it's my favorite is because it displays in the URL bar the pagerank of the site I'm on. It's like an instant credibility check whenever I'm browsing or reading an article. In fact, browsing without it (say on my phone or in my newsreader) now feels like an incomplete experience.

My favorite extensions in Firefox are tied, Firebug and the Web Developer Toolbar. I'm sure if either got a full-fledged extension in Chrome, it'd probably be my new favorite extension.

Firefox.

It turned out I couldn't live without Ubiquity. Still under development, although officially it's on hiatus.

The Add-On Compatibility Reporter, so I can run edge versions of extensions.

Firemacs (for sensible Emacs bindings)

TabKit (tabs on left side and tree style, with grouping and so on) and Ctrl-Tab (LRU tab switching, plus thumbnailed tab display and switch to tab by name-typing). All other tab organization systems pale in comparison.

And the rest: NoScript * Firebug * Web Developer Toolbar * Greasemonkey * IETab * Vacuum Places DB

Gmail Checker (Official one by Google)

Rapportive

Chrome 2 Phone

Google Voice

Lastpass

Google Reader

Craigslist Comprehensive Cleanup

Craigslist Preview

Facebook Photo Zoom

Extension Gallery Inspector (Invaluable if you want to know what an extension is going to do BEFORE you install)

TackyNotes (I should note that I don't really use this, I just have it installed because I wrote it. I suppose the fact that I don't use it is a good indicator of why I've lost interest in developing it. They say it's best to write software to fix a problem you have or someone else has and I think that kind of missed the mark.)

Chrome dev channel:

AdBlock

Aviary Screen Capture

Awesome Screenshot - (to capture the whole page)

Better Facebook Fixer

Chromey Calculator

DayHiker - For Google calendar. Check schedule and tasks from toolbar.

Docs PDF/PowerPoint Viewer (by Google)

Forecastfox Weather

Gmail Notes (Beta) - Add notes to conversations in Gmail and save these notes to Google Docs.

Gmail StrikeThrough - Enable StrikeThrough in Gmail or Google Apps Mail.

Gmail Unread Message Count in Favicon

Google Calendar Dynamic Icon - Changes the number on the Google Calendar favicon to reflect the current date

Google Chrome to Phone Extension

Google Mail Checker Plus

Google Voice (by Google

Graph Your Inbox - Visualize your Gmail data.

Novell Moonlight

Rapportive - (Disabled)

Speed Dial

Tab Sugar

Firefox: Firebug, Pagespeed for finding slowdowns in my pages. WebRank toolbar for when I'm too lazy to open Market Samurai.

Chrome: Eyedropper for stealing a color. Nofollow eyes to make sure my pages aren't wasting pagerank. SEOQuake for when I'm too lazy to open firefox/MS. Ultimate Chrome Flag. I like seeing ips/locations/etc. Chromed Bird for my twitter accounts that are for business.

AdBlock, FlashBlock, Readability and Instapaper. The web is an obnoxious assault on the senses. There is some useful stuff in between all those flashing billboards and neon lights so I block all of the distractions that I can. I wish there was a SocialNewsBlock plugin to get rid of all of those damn buttons everyone puts on their sites, too.

On chrome i use:

* Notscript (blocks javascript, not as good as noscript for firefox but imho still good)

* Adblock

* Navigate on paste (load webpage with middle click on linux)

* Type ahead find (just start typing to search)

* android2cloud (send urls from your mobile phone to your browser)

For Firefox:

* TabMixPlus (Multiple rows for tabs)

* NoScript (JavaScript blocker)

* AdBlock Plus

* FoxyProxy (easy managable proxys)

* AutoAuth (automatically submits saved http basic authentication dialogs)

* Locationbar² (easy access to url segments)

* Firebug

I use many of the ones people have mentioned here, but in Firefox. Can't switch to Chrome because it doesn't have a good implementation of two of my favorite add-ons:

Stumbleupon - for whenever I need a distraction that even HN can't fullfil

Colorzilla - For getting colors of web pages; use this about a dozen times a day

Vimperator - make Firefox more like Vim

Just the important ones:

BetterPrivacy (LSO Cookie Remover)

Firebug (+ Firecookie)

Hackbar

NoScript

Tree Style Tab

Web Developer Toolbar

All of which have no (satisfactory) Chrome equivalent and thus prevent me from switching ;)

The only one I use that hasn't been mentioned here yet is Venkman (JavaScript Debugger) for FireFox.

For Safari:

Gmail Checker - Adds an icon to the toolbar with a badge of how many new emails I have.

Helvetify - Forces Helvetica Neue as the font for all websites.

Facebook Photo Zoom - Zooms photo thumbnails on Facebook so you don't have to reload the whole page when you want to see a photo.

On Chrome:

Adblock, RSS Subscriber (puts an RSS icon on the location bar where relevant and allows you to subscribe to the feed).

I also wrote my own delicious extension to easily add bookmarks into delicious.

On Firefox: Firebug, Adblock

I basically only use firefox these days for debugging web apps.

What is the FF extension called that lets you type to search the addons you have and also lets you see a text list of all the addons you have (enabled and disabled). I used to have it but I switched computers...

Since I like a fast, non-cluttered, browser I have only one addon installed in Chrome. "No More Tabs" protects me of opening 40+ tabs and telling myself all the time "Don't close it, you might need it again!"

Firebug

Greasemonkey

S3Fox

ColorZilla

DownloadHelper

Vacuum Places

... and a shameless plug for Compass, a Firefox/Chrome/Safari add-on I wrote that adds a "table of contents" to various e-commerce sites to help you find stuff faster. Search for "compass" on the various extension galleries if you're interested.

AdBlock Plus, ColorfulTabs, Downthemall, FaviconizeTab, Favicon Picker 3, Greasemonkey, Greasefire, IdentFavicon (obviously, I am into icons), Quickpagezoom, TabRenamizer

Different at work and at home. Of the ones not already mentioned here my favorite is Add Bookmark Here. Adds some very simple functionality that is sorely missing.

AdBlock Plus and FlashBlock. Mostly to avoid distractions.

I also occasionally use Helvetireader: http://helvetireader.com/

I use lasttab in Firefox to get LRU tab switching. Until chrome gets it (and don't make me change my ctrl-tab muscle memory) I'm not switching.

Chromium:

After the Deadline - Version: 1.2 Check spelling, style, and grammar in your browser

Boomerang for GMail - Version: 0.5.0 Allows you to schedule messages to be sent or returned at a later date.

Chromed Bird - Version: 1.8.5 Chromed Bird is a Twitter extension that allows you to follow your timelines and interact with your Twitter account.

ChromeMilk - Version: 0.9.6 Access your Remember the Milk tasks right from your Google Chrome toolbar

Docs PDF/PowerPoint Viewer (by Google) - Version: 2 Automatically previews PDFs, PowerPoint presentations and other documents in Google Docs Viewer.

FastestChrome - Browse Faster - Version: 3.1.2 Save time and enhance your productivity! Get quick definitions, auto-load next pages, search faster, and more.

Google Calendar Checker (by Google) - Version: 1.0.3 Quickly see the time until your next meeting. Click the button to open your calendar.

Google SSL Web Search beta (by Google) - Version: 1.3 Use Google Web Search and Suggest protected by SSL.

Google SSL Webcache - 谷歌加密快照 - Version: 1.21

IE Tab Classic - Version: 0.9.5 Internet Explorer inside Chrome

Mini Google Maps - Version: 1.0.2 Google maps in a click away.

OmniTweet - Version: 10 An experimental minimalist Twitter Client for Google Chrome.

PostRank Extension - Version: 0.1.4 Filter your Google Reader inbox with PostRank to find and read what matters. Or enhance Digg, Reddit, & search with PostRank.

Rapportive - Version: 1.1.1 Making email a better place

Secbrowsing - plugin version checker - Version: 1.7 Periodically checks that all your plugins are up-to-date.

Secure Login Helper - Version: 1.2 Attempts to help you login to sites using SSL if possible.

Send using Gmail (no button) - Version: 1.11.4 Makes the Gmail webmail your default email application (original Google extension repackaged without toolbar button, safer links)

Sexy Undo Close Tab - Version: 6.17 Undo your closed tabs (cleaner version) + new features

Stop Autoplay for YouTube. - Version: 0.10.7.30 Stops YouTube autoplay but allows pre-buffering.

Unsubscribe for Gmail - Version: 0.34 Rid your inbox of unwanted email subscriptions with the click of a button!

WiseStamp - Email Signatures for GMail, Google Apps and more - Version: 2.0.3.0 Empower GMail, Google Mail & Google Apps emails with dynamic email signatures. Add Twitter, Facebook, Digg and more. Multiple HTML signatures support.

Chrome: StayFocusd Awesome Screenshot Capture Rapportive

Firefox Firebug Tamper Data YSlow

Bookmarklets Delicious Zemanta Read Later (instapaper) bit.ly sidebar

FireBug, Delicious, Tails Export and Operator mostly cause I make sites not so much as consume them...

In alphabetical order:

BetterPrivacy, Certificate Patrol, Firebug, Flashblock, iMacros, Sage, Tamper Data

iMacros is particularly useful.

Firefox: Vimperator, Xmarks, Zotero, Firebug, Rainbow, Speed Dial, Moonlight.

Chrome: Vimium, Web Developer Tools

try https://chrome.google.com/extensions/detail/gkjgmeeoldebbdoe... TweetRight - a new chrome extension for twitter users.

I keep it simple. Xmarks, adblock (adthwart on chrome), and sometimes greasemonkey.

Chrome: Awesome Screenshot Google Voice Session Manager Stumbleupon Gmail Checker

Firefox: Delicious Bookmarks, Autopager, Greasemonkey, FoxClocks

Chrome: Google Voice, Google Mail

Chrome: Polyglot to help me learn hanzi, and ProxySwitchy to bypass the GFW

hckrnews for Hacker news:

    * Highlight new comments in a thread.
    * Collapsible comments

Firefox (stuff I haven't seen on here yet): * Ubiquity * Fox to Phone

FireBug, AdBlock and sometimes NetVideoHunter to download videos.

FireFTP for Firefox.

Chrome.... probably FireFTP if it ever exists for Chrome.

Chrome: LastPass, Google Voice, Google send to phone.

Chrome:

AdBlock

FlashBlock

Google Analytics Opt-out (not sure why :)

Google Mail Checker Plus

iReader

Modified keyboard navigation for Chrome

Rapportive

-

Firefox: FireBug, YSlow, Page Speed.

Chrome:

AdBlock

BugMeNot Lite

FlashBlock

KB SSL Enforcer

LastPass

QR-Code Tag Extension

Readability Redux

Smooth Gestures

SmoothScroll

Vimium

Webpage Screenshot

Xmarks

----------

Firefox:

Adblock Plus

Add to Search Bar

Combine Buttons

Firebug

FireGestures

Flashblock

FlashVideoReplacer

Greasemonkey

Hide Menubar

HTTPS-Everywhere (Development branch)

LastPass

Menu Editor

OptimizeGoogle

Organize Status Bar

QuickRestart

Screengrab

Stop-or-Reload Button

Stylish

Tab Mix Plus

Tabs on top

User Agent Switcher

Vimperator

Safari:

Shortly

ClickToFlash

also use

ghostery

https://chrome.google.com/extensions/list/popular

Next question.