ypelletier:
I built a MIDI controller with an old organ keyboard, an Arduino and two hc595 shift registers. It is documented in my blog (it's written in french, but maybe the sketch and schematics will be of some help?)
I read French (I live in France) and my native language is English. If you are interested to have parallel French and English versions of those Arduino MIDI blog posts, I would be happy to translate them for you.