[Alison Lewis] has posted this fantastic digital wall harp project at My Home 2.0. They built an infrared MIDI instrument into a wall, using a MidiTron and some IR sensors. It all connects to a computer running a MIDI sequencer via a MIDI to USB converter. The project was built for a family home. They wanted something musical that they could play as easily as waiving their hand. They got it! Simply run your hand under the sensors and play some music!

[via Instructables]