Hulu went live, last week I think. Has high quality clips from TV shows and movies, as well as web stuff. Also has full TV episodes and movies, so if you're a Bob Newhart Show fan but don't want to commit to the DVDs, you've got episodes here. Not sure if they last forever, or how often new seasons are added.
There are ads, which can be annoying while going through Conan O'Brien clips, but they're not as bad as boradcast ads if watching a TV episode, only 30 seconds a shot.
UPDATE: Hmmm, embedded videos rather wide as you can see, and unresponsive to my HTML adjustments. So they may show up wonky if embedding.