Blender

Blender is a free 3D computer software program used for creating animated films, visual effects, interactive 3D applications or video games. Blender's features include 3D modeling, UV unwrapping , texturing , rigging and skinning , fluid and smoke simulation, particle  simulation, animating , rendering , video editing  and compositing <span style="color: black; font-family: 'arial','sans-serif'; font-size: 13px;">. It also features a built-in <span style="font-family: 'Arial','sans-serif'; font-size: 13px;">game engine.

Blender's animations systems supports a variety of techniques and tasks, allowing the creation of complex animations. The Interface allows you to change, adapt and re distribute the layout of all UI components and tools to suit the task at hand. Coupled with modifiers like multi-res, the models can be very complex while the interface remains responsive.Because these tools are available within Blender itself the production is greatly streamlined, and with GLSL support the results are instantaneous

Currently, there are versions of Blender available for Windows (2000,XP, Vista), Mac OS X, Linux (i386 and PPC), Irix 6.5 and Solaris 6.8. You will also need an OpenGL compatible graphics card, preferably from a quality vendor such as NVidia or ATI.