Miduino

I found this when looking around the Arduino site. It looks like it could be a lot of fun to play with. Here's some info:

The MIDUINO is a combination of MIDI (Musical Instrument Digital Interface) and the Arduino, which is based around the ATmega168 microcontroller. The Miduino is a breadboardable Arduino clone. The Miduino design kit comes with an ATMega168 pre-loaded with bootloader. The design can be utilized for general microcontroller projects or for specific MIDI designs.

The board design comes with a built in Opto-coupler and 4-way DIP switch which allows MIDI IN and easy setting of MIDI channels (1-16) if required. MIDI out is also available. The Miduino board is designed to be expandable. So MIDI IN is looped to MIDI OUT, on all the board designs.