This DIY MIDI Fighter controller is a brilliant example of a project that is a relatively simple build, yet is a polished final product.
The relaunched Atmegatron and its little brother the miniAtmegatron are 8-bit chip-tune synthesisers based on the Arduino.
The Multi-Touch is a touch controller featuring an 8×8 grid of LED loveliness.
The RN-9090 is an extremely well-built MIDI step sequencer that outputs pure MIDI to control external synths.
The Guitarduino is an Arduino based guitar project that lets you trigger loops and effects while you shred.
The Meganome is a DIY MIDI controller created by Patrick Flanagan featuring an array of LED arcade buttons, and continuous controllers.
The Toa Mata Band is a collection of Lego Bionicles that play various musical instruments. They play drums, synths, glockenspiels and more!
The Arduinome is an open-source clone of the Monome with easy to obtain parts. The result is similar to the Monome, but with RGB LEDs.