Ryan Raffa completed his Physical Computing and Max MSP project with an Arduino based beat control device. Using an ADXL 335 AccelerometerADXL 335 Accelerometer interfaced with an Arduino, The device sends commands to the Max MSP software to play a certain track and add delay as the user sees fit.
All source code is available at his website, get it for reference at least.
For all DJs out there, this might be a fun way to pick up the beat at your next party. And it will look like you are doing more than just playing tracks off your laptop. (I miss the vinyl days.)
Dig