www.hulu.com
Hulu is still in beta, but it looks like a pretty promising site. You can find information about the site here. The video sharing thing seems like the best part. I like how you can choose exactly where and when you want it to stop. The videos are all pretty high quality, too.
I signed up for the beta testing, and watched a few episodes of The Office and It's Always Sunny in Philadelphia. You guys should sign up for the beta, because you can find full-length episodes of almost any show. This is legal, btw.