OpenFX

This powerful 3D modelling application was previously known as the commercial package SoftF/X. The author has decided to release the code under the terms of a GNU General Public Licence. It's a very tasty application and includes a full renderer and raytrace engine, NURBS support, kinematics-based animation, morphing, and an extensive plug-in API. It is a truly massive download, thankfully there are two smaller versions including a 'tiny' version which just contains the essential applications. You won't find a better 3D renderer unless you start making serious financial investments. Thank you Dr. Stuart Ferguson.