At CES, we had the chance to get our hands on Razer/Sixense's new motion controller for PC, which to this point does not have an official name. These controllers are pretty sweet peripherals. Using magnetic technology, they have significantly more accurate accelerometers than Nintendo's Wii remote, meaning they don't require all the recalibrations the Wii often does.
We were able to play Left 4 Dead 2 using one of the Nunchuk-shaped devices, and it worked surprisingly well. The demo showed off a number of different ways in which the controller could be used -- as a standard mouse with motion functions (swinging it for melee attacks, etc.) to more motion-centric designs.