Free Software for the Aspiring CG Enthusiast

Everyone likes free stuff.

Maya Personal Learning Edition
Autodesk 3DS Max 30-Day Trial
Blender 3D (Open Source Modeler)
ZBrush Trial
Houdini Apprentice
Renderman for Maya Evaluation
3Delight (Renderman Compliant Renderer)
Pixie (Open Source Renderman Like Renderer)

Just a start... There's also a bunch of open-source renderers avalable out there as well.