Man, I just came across these two sites that are guaranteed to make you laugh.
The first one is darejunkies.com.
At Dare Junkies they post dares that people accept and film and upload to the site. Once all of the videos are uploaded people vote for a winner who receives a cash prize.
The second site is jibjab.com. They have a lot of different comedy animations and such. I recommend starting with their most recent production labeled Nukin Futs which is a very cool and funny 2006 year in review.