One of the teams participating to the MIT Media Labs Design Innovation workshop at PESIT Bangalore last January built something called Beat Feet using Arduino Uno:
"We designed a system which will allow musicians, guitarists and keyboardists to set the beats according to the music they play, without getting up from their place or even without lifting their hands off the instrument! Yes, simply by tapping foot at a constant rate. Donāt believe it?"
Beat Feet allows musicians to add drum and guitar effects using only feet gestures and wearable sensors. Check the details of the project on this website and watch the video to see it in action!