Papervision 3D - flash 3D stuff.

Have you seen this link: www.papervision3d.org ? If not you should go and admire something beautiful created in 3D.
It is designed with the flash.
The rapidity with which objects are rendered very good.
Papervision3D  has integrated QuadTree support and many features.
You can download this engine from here.
See screenshot below :