I have a dell mini 9, its great for college and checking email. Also good for light web browsing. Its not great for programming because the keyboard is a bit to small.
It works great with the new "cloud" web apps like dropbox and google docs offline.
Nah. Netbooks don't have enough CPU cycles or pixels to keep up.
Granted, I haven't owned one, but I do more than browse the internet. Netbooks typically can't provide enough horsepower to run all of the programs I like to run at the same time.
I have an eeepc, but you couldn't do any serious amount of work on it. I'm not so concerned about the horsepower (if your software is so bloated it doesn't run at speed on an eeepc, which is way faster than my main development machine was only 4-5 years ago, you're doing it wrong.)
The main problem is the screen real estate and keyboard size. I just can't type at speed on the eee, I keep hitting all the wrong keys and it gets very frustrating. It's fine for the odd email, but no way could I crank out the code on it. The screen is also too small. My main laptop has a nice widescreen where I typically have 2/3rds IDE and 1/3rd documentation/consoles. Not possible on 7-8" screens.