Take a look at dojox.gfx: docs, tests, demos (last two links to the nightly snapshot on the test server optimized for debugging, not for production).
It uses native graphics: SVG, VML, Silverlight or Canvas — whatever is available on the client covering all major browsers (IE, Firefox, Safari/Webkit, Opera).
While it is 2D, it can be used as a foundation for 3D stuff. In fact there is a library that takes advantage of it: dojox.gfx3d. Examples (can be found in tests):
- cylinders
- cube
- pilot test
And for truly adventurous types there is a library done for Dojo as part of Google Summer of Code 2008: True 3D. Obviously it is much faster than 2D/3D hybrid, and suitable for fluid animation. You can explore it on your own (the previous link is a publicly available Subversion repository), but be warned: it works only on Firefox and Opera with special 3D graphics add-ons from respective vendors. You'll find all gory details in the documentation.
Have fun!
