Joost is a relatively new online (free) TV service, with over 256 channels - it looks really good! Joost is slowly incorporating social networking widgets into it's player interface (available for Mac & PC). The free view is paid for by pop-up advertising. Joost requires a good broadband connection with a decent data cap and a relatively new computer with a decent graphics card (not sure how the MacBooks will fare, but the MacBook Pro works great!).
I enjoyed some Aardman animations and some SciFi last night :D . Apparently there is integration planned for Meebo & Joost for social networking!