The Nintendo wii remote (wiimote) undoubtedly the second coolest invention since the bathtub. The only difference is bathtubs can't be used to control Mixxx (atleast not yet!), but the wiimote can be!
How this works is glovepie interprets signals from your wiimote that is paired with your computer over bluetooth. These signals in glovepie are converted to midi events that are THEN sent through the virtual midi device to mixxx! Mixxx then uses these events to control whatever you can imagine (such as turning the wiimote to trigger the crossfader based on the position the wiimote is at). Wow!
Okay, so thats a pretty straightforward (I hope :S). It does require a fair amount of configuration and scripting to make it work. Its not as easy as downloading the above software, installing, and going nuts with your wiimote to play music. Glovepie must be scripted to capture specific events, such as hitting the 'B' button or using the built in accelerometers with movement. Glovepie comes with several script files that have various examples of different usages that can be examined to add to your own script.