Synapse, Dj dance controls music Djing
Two weekends ago, Ryan Challinor released Synapse, a working Kinect application (for PC and Mac).
It is free and available for download @ SYNAPSE for Kinect - Synapse for Kinect
You just need a Kinect device (no Xbox required) and Ableton’s Live 8.2 installed for it to function. It does skeleton tracking and follows movement’s depth, so you may actually do dance moves to control the music 
There’s a video Synapse video
And a timed post about it at Kinect official developer’s forum