I have just seen these nice short animations that have been made in the free 3D program Blender.
I did not like the animation in Elephants Dream but the ideas and design are awesome.
Big Bunny Buck had a nice story to it and looked great throughout.
And the trailer for Sintel looks amazing, I cannot wait to see the final film!
Elephants Dream, 2006
Big Buck Bunny, 2008
Sintel Trailer, 2010