FreeWRL is an Open Source, cross platform VRML2 and X3D compliant browser, with script, SAI and EAI support. Platforms supported: Linux and other Unix-style platforms; Mac OS/X; Windows. Support for mobile platforms (iOS, Android, QNX) is under development.
...Blender is the open source software for 3D modeling, animation, rendering, post-production, interactive creation and playback.
Available for Windows, Linux, Irix, Sun Solaris, FreeBSD, Mac OS X, and soon for the Sharp Zaurus.