This is my first Arduino project: It is a rework of a simple sequencer which uses capacitive sensors that I originally implemented on a Picaxe. I'm amazed that this project only using 3 resistors, a piezo speaker, the arduino (of course), and a few hours of programming time.
Details at: http://corticalcafe.com/arduino_beatbox.htm with an obligatory youtube vid, (though its certainly not as exciting to watch as a bot video!).
Many cool projects here!