Ctrl-click or Command-click is the answer.
When you click a link, it opens in the current tab.
When you middle-click a link, it opens in a new tab (in the background).
I HATE sites that go against this, and decide for me where to open the link. Especially since Chrome has an outstanding bug where middle-clicking links with target attributes opens then in a new foreground tab. So annoying.
I agree with others that this doesn't make sense to become a default. However, it doesn't mean that's your only option. http://userscripts.org/scripts/show/57563 looks like it might do the trick (although I haven't tried it). If not, it shouldn't be too difficult to create your own GreaseMonkey script and solve your problem.
here I thought you were going to ask for higher contrast text in the Ask HN: posts. :)
I generally hate having sites "decide" this for me. This is almost certainly a personal preference.
When I use Atomic on the iPad I set it to open off-site links in new tabs. Yet on my desktop, I never do. This is a setting in various browsers.