AS3 3D Physics Engine : WOW-Engine
Now we have a 3D Flash Physics Engine. There is already some basic physics support in Away3D but this one looks much more promising. It’s based on several famous open source flash products. It extends the APE 2D Physics Engines and uses Papervision3D for rendering.
Flash Components.net
The Flash Components Network is a marketplace where you can find many simple but useful tools for your flash projects. Most of the listed items are commercial but the average price is really modest.