Blender, K-3D, Art of Illusion and Google SketchUp are some of free applications that are useful for 3-D animation, modeling and rendering. ZModeler is particularly useful for modeling computer games, whereas Google SketchUp 6 is useful for creating, sharing and presenting 3-D models.
Blender is a free, open-source 3-D modeling application that is also useful for UV unwrapping, texturing, rigging and creating water simulations. K-3D is an excellent application for polygon modeling. Skeleton-based animation and subdivision surface-based modeling tools are some features that Art of Illusion offers. Google SketchUp allows for easily building models of Google Earth, presentable in image, movie or print formats.