I went to SIGGRAPH this summer (a computer science conference about graphics) and they have an animation festival. My favorite three are
1. The Wonder Hospital.
This awesome video won the best student film award, and it deserved it.
The whole video is not available, yet.. Keep looking at Shimbe.com
Here is a clip:
Creepy, surreal and terrifying, there is only a clip online:
Funny and clever, it presents a world made of logos.