Instructables staff member Randy Sarafan has documented one of the largest Arduino-based projects we have seen for some time, his Robot Drum Kit. It isn't a bunch of robots playing the drums, instead each drum is played by an Arduino with two drumsticks controlled by car door lock motors and motor shields. Making the system play is a sequencing program for MAX MSP which controls the Arduinos via USB. The entire project is simply amazing and worth a look here:
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