Here is a really cool project: a drumbox that run on arduino and can function both as a standalone and as a midi controller
Made by Amanda Ghassaei, this really is a step by step project of a functioning D.I.Y. drumbox! There are a lot of thing to learn in this Instructable: how to setup an audio output on an Arduino, how to amplify it, how to multiplex button, how to load sample on the Arduino... In the next upgrade of my Orbital, I'd love to make it a standalone drumbox and this Instructable really gives me solutions to do it!
More informations here
And here is Amanda Ghassaei personnal site.