NetDevil's PhysX-powered, totally destructible (mostly) shooter Warmonger, Operation: Downtown Destruction is now available for free download on the official site.
It's worth noting that not only is the game free, it doesn't actually require AGEIA's PhysX card to play. You need the card to get the total experience, but don't let that stop you from checking it out if you don't have one.
Here are the official requirements:
CPU: Intel Core 2 Duo Processor E6400 (2MB L2 Cache,2.13GHz,1066) or equivalent
RAM: 2GB RAM
GPU: Nvidia 7900 graphics card or equivalent
PPU: PhysX 100 Series Processor strongly recommended, with system software 7.11.13 or later
HD: 1.8GB of available space