BFG Ageia PhysX Card
 

FG is one of two companies offering the Ageia PhysX card in form of a retail product. The PPU - physics proccesing unit - is an additioal processor to the GPU and CPU. It enables real life physics and interactivity within supporting games. While the first games and a high price tag upon launch did not live up to expectations, the brand new Ghost Recon Advanced Warfighter 2 and a very affordable 120 USD price tag makes this a great addition nowadays.

http://www.techpowerup.com/reviews/BFG/Ageia_PhysX_Card