Cracking little indie game coming up called Wrack (inspiration from Quake of course) - cel-shaded single player (yes, really!) FPS that's really making some people pay attention in the gaming world. It's certainly quite fun anyway.
Their site is Wrack - The Cel-Shaded, Arcade-Style First-Person Shooter , worth a look IMO. If you like things like Serious Sam and Quake/Doom then this will probably tickle your fancy.
We're also doing a developer chat with them over on Quakenet this Thursday but I won't go into details for fear of being told off