Mac users interested in Renderman app for mac os x generally download:
Aqsis is a cross-platform photorealistic 3D rendering solution, adhering to the RenderMan interface standard defined by Pixar Animation Studios.
The Aqsis project itself consists of a number of components, each separate in their own right, but contributing to the larger aims of the project as a whole.
K-3D is free-as-in-freedom 3D modeling and animation software. It combines flexible plugins with a visualization pipeline architecture, making K-3D a versatile and powerful tool for artists.
K-3D's interface uses your platform's look-and-feel, and it's consistent with the applications you already know.
3Delight is a fast, high quality, RenderMan®-compliant renderer designed to produce photo-realistic images in demanding production environments. The renderer was introduced in 2000 and is now widely used in the industry. Because of its high versatility and speed, 3Delight has earned a reputation as a benchmark in rendering technology.