I use GLC Player as a viewer for 3d files.
http://www.glc-player.net/
If you know better viewer for 3d files, please share the links.
Cheers.
Edit:
I found the 3DBrowser.
http://www.mootools.com/plugins/us/3dbrowserlight/index.aspx
But this is for windows only.
I need the one for mac.
