The Lonely Island: Some kids from california or something, but there awesome. Watch their films and look for Ardy on Saturday Night Live
Cyber-Crack.net: Wolfe's brothers site, lots of great movies, go watch them now! (PS: wolfe and eben are in The Chronicles of Riddickulus)
Mega64: A few guys who make movies about video games. A few are really good, like Metal Gear.
Naked Castle: Suichine is pretty good and the ty-dye samurai are good, but other then that, there awful. Enjoy!
DMack Productions: My friends site consisting mostly of claymations. They rewl!