I've yet to see convincing evidence that a first-person shooter (or indeed, any kind of non puppet-based shooter) could work on the Xbox 360's Kinect motion controller. That said, if I had to pick an FPS that would work well with the hardware, it would probably be People Can Fly's highly physical Bulletstorm.
So it's nice to see that the guys in the video above used FAAST (Flexible Action and Articulate Skeleton Toolkit) to make a hack that lets PC Bulletstorm players control the game with their hands and feet.
In the video, you'll see the picture-in-picture player controlling the shooting and gun motions using his hands. But also, he can lash out the game's "leash" and kick out his left foot and cause his on-screen character to kick as well. Few games would benefit from a real-foot kicking option as much as Bulletstorm would, and despite the fact that I'd still rather play it with a controller, I could see myself trying this. Given that Kinect is officially coming to Windows PCs, I bet we can look forward to a lot more creative applications like this one.