Midi_monster is a project mainly written in C, it's free.
Code for the DorkbotPDX/Don Davis Midi Monster [USB + MIDI]
requires LUFA 091223 http://www.fourwalledcubicle.com/LUFA.php
Code is for the Dorkbot PDX workshop #2 [for now]
Edit the makefile to work on your system [edit the LUFA_PATH]