If you like comedy, watch the Simpsons, Family guy, South Park and Futurama on Hulu.

If you like drama, watch Dr.House and Grey's anatomy on Hulu.

Also click onto the Popular Shows and Popular Episodes and see what Hulu TV shows and TV episodes are the most popular.

Note that you can not only watch, but also download Hulu videos onto your computer:
How to download videos from Hulu.com onto your computer?

Hulu is available to US residents only. But you can overcome geographical restrictions and watch Hulu from outside the USA:
How to access BBC iPlayer, Hulu, Fancast, Pandora, any other region-restricted sites