I spend most of my online time here, and at the Drupal support site. After that probably comes Wikipedia, then BBC news, usually. I also regularly frequent Google (but not for long periods of time, due to its nature) and occasionally spend a chunk of time at Amazon or Powells, but I'm too poor to do that often.
I used to spend a lot of time at the Second Life forum, but I haven't had time to play Second Life for a while, so that's dropped off my regular visit cycle. Same with wilddivine.com, which has forums for a biofeedback game I have, and tabletpcbuzz, which I was into for a while when I was trying to rig a tablet on the cheap. I guess sometimes I'm a bit fickle in my interests.
Oddly enough, I don't think I've ever been to FaceBook or MySpace, though maybe I've hit some pages on the latter because some authors and other businesses use it.