K-3D Three Dimensional Modeler/Animator for Windows or Mac X or Linux http://www.k-3d.org/
K-3D is a complete free-as-in-freedom 3D modeling, animation and rendering system.
K-3D features a robust, object oriented plugin architecture, designed to scale to the needs of professional artists. It is designed from the ground up to generate motion picture quality animation using RenderMan compliant render engines.
We strongly recommend the Aqsis render engine for use with K-3D.
K-3D is the free-as-in-freedom 3D modeling, animation, and rendering system for GNU / Linux, Posix, and Win32 operating systems. K-3D features a robust, object-oriented plugin architecture, designed to scale to the needs of professional artists, and is designed from-the-ground-up to generate motion-picture-quality animation using RenderMan-compliant render engines. We strongly recommend the Aqsis (http://www.aqsis.org) render engine for use with K-3D.
K-3D's innovative interactive tutorial system will introduce you to basic use of the program. New tutorials can easily be recorded and shared with the rest of the community.
K-3D allows you to create and edit documents in multiple realtime OpenGL solid, shaded, texture-mapped views. You can even model, animate, and interact with animations while they play back for maximum productivity!
You Use the K-3D Modeler and the Aqsis 3D Rendering Engine TOGETHER - and You DON'T Need to Spend $3,500 (Three Thousand Five Hundred Dollars!) for Renderman®