Art of Illusion is a free, open source 3D modeling and rendering studio. It is written entirely in Java, and should be usable on any Java Virtual Machine which is compatible with J2SE 1.4 or later.
Art of Illusion is 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.