Blender is a high quality 3D modeling, rendering and game creation application. It is open source and available for Linux, Windows, Mac and other platforms. Back in 2002, I donated $50 to help the cause to open source Blender. It was one of the best investments I've made.
Other things I've made in Blender
- http://www.blender.org/ - Official website
- http://www.blenderartists.org/ - A site that includes a popular forum.