Hulu and Hulu Plus. Hulu Plus requires a subscription
Netflix: TV and Movies, Classics to present. Some content in HD and 5.1. Needs a paid subscription
Crackle.com: TV Shows and Movies. Free to access
ITV.com: ITV Player shows such as Penn and Teller Fool Us
CBS.com Video: Big Bang Theory, CSI, Two and a Half Men and more here.
TBS.com Video: Shows such as The Fresh Prince of Bel Air, American Dad
ABC.go.com: Shows like Suburgatory, Modern Family
au.tv.yahoo.com: Watch later episodes of programmes like Home and Away, Packed to the Rafters
NBC.com Video Library: 30 Rock, The A-Team and more here
thewb.com: Shows like Gilligans Island, One Tree Hill
USA Network: Psych and more
Universalsports.com: Seems to be just highlights of various sports
Channel4.com 4oD: Allan Carr, Come Dine with Me and lots of other interesting TV
The above are just some of the sites that have video on demand. There are others, but they require a cable subscription to be able to view.
Pandora: Choose your artist and it will play them along with similar style artists
Songza: 100% free, Music playlists by experts, No audio ads. Definitely worth a look
Turntable: Play Music together. Requires a Facebook or Twitter account
Jango: Like Pandora but with unlimited skips. Recommended
There are others, but easy to find, especially if you use Chrome Browser with the similar pages extension.