I made a couple simple demos for the VIS145A students at UCSD to show how we can use an iPhone as the interface to Processing sketches.
Teach your baby to be a hip hop producer early. This is a MIDI drum kit that I made using a microcontroller and another $2 find at Savers.
Just a quick experiment to show that the NESpad library I wrote for the Arduino microcontroller actually works. An NES Advantage joystick acts as a mini MIDI drum pad.