While the PS3 is already pretty friendly to most mouse and keyboard setups, the XFPS Rate Up Adaptor (formerly just for the Xbox 360) is a peripheral that allows you to remap SIXAXIS controls to your stubborn PC ways of old and control any game as you would a computer title. It's completely plug and play and supports 95% of keyboards and mice on the market. Wait, we just read this thing is $US 100. Seriously? Maybe you could justify the purchase when combined with a backward compatible PS3 that could add mouse control to PS2 titles. But we're betting that $US 100 would probably look better sitting somewhere inside your PC.
XFPS RATEUP for PS3 [TotalConsole]