If you're a developer and you've ever used Google to find some code (uh…who hasn't), GO SIGN UP FOR KRUGLE RIGHT NOW!! I signed up about 2 months ago and just finally got in on the beta. It's amazing. You can watch the demo (800×600) to get an idea of what you're waiting for.
The interface is great; it's an Ajax app and beta so there are still some issues (*ahem* BACK BUTTON) but impressive and intuitive nonetheless. It supports a variety of languages from Objective-C and LISP to TCL and sh. There's something in there for everyone.
If you sign up, please leave a note and let me know what you think.
*** UPDATE: It appears that the beta is closed at this point. Be sure to sign up so that you'll know when it officially rolls out. ***