Blender is a sterling example of what can be done within the GNU
free software movement. It doesn't have to hang its animated head
in the presence of any commercial animation programs. The work it
turns out is vividly detailed--check out the screenshots--and
movements are convincingly smooth. It is frequently used to build
developers to build complex avatars and environments on sites like
IMVU.com, a 3D chat system.
The reason is pretty simple: Blender has all the features you
need to produce interactive 3D graphics and games that are
compatible across platforms. Its suite of features allows modeling,
rendering and postproduction polishing.