The MidiDuino library for the Arduino is a port of the MiniCommand functionality. Send, receive and synchronize to MIDI streams, and access the power of the Ruin & Wesen MiniCommand on your Arduino.
Attach your own sensors, build crazy sequencers, and control your physical computing applications using MIDI.
The library is available for all ATmega328 and ATmega168 based Arduinos, support for Arduino Mega is in the works. The additional core allows supertight MIDI synchronization.
Quick fix: for arduino 0018, replace all the calls to putc with calls to RWputc.