Art of Illusion is a free, open source 3D modeling and rendering studio. This is stable and powerful enough to be used for serious, high end animation work. Many of its capabilities rival those found in commercial programs. Some of the highlights include subdivision surface based modeling tools, skeleton based animation, and a graphical language for designing procedural textures and materials.

It is written entirely in Java, and should be usable on any Java Virtual Machine which is compatible with Java 5 or later.

It looks quite simple in terms of its User Interface but you will be surprised to view the Samples made with this Free 3D Modeling and Rendering Software.

Website: http://www.artofillusion.org

Download: http://www.artofillusion.org/downloads