Elephants Dream is a cool computer-generated 10 minute film created using open source software – mainly Blender. It’s licensed under the Creative Commons. I’m not sure exactly what it’s about and what the storyline is (beyond me) but the graphics are pretty impressive and look fantastic.
It reminds me a bit of Blue: A Short Film which is a 23 minute CC-licensed CG short film. Blue is "a sci-fi adventure about a small robot who wakes up all alone on a space station and gets into more trouble than he can handle". You can get it at LegalTorrents.com.