http://www.penny-arcade.com
Penny-Arcade is a hilarious webcomic if you're hardcore into gaming. If you aren't, you can still go there for an occasional laugh, but you might not get a lot of it.
http://www.homestarrunner.com
Home Star Runner is another funny one. But you should've gone there already. A long time ago.
http://www.newgrounds.com
Newgrounds is a flash movie portal with a LOT of great stuff on it. A lot of porn ads, too, so be careful.
EDIT: HTML doesn't work. wtf.