Hi! I have coded a theremin app for Android phones called Tilt Theremin. It uses motion sensors to control pitch and volume. The latest version supports gyroscope sensors, which makes it more intuitive and more like a real theremin. The gyroscope sensor is available on most newer devices running Android 3.0 or later.
I would love to hear comments and suggestions from some of you who may have an Android phone, or who would check out one of the videos I have made with it.
Instructional video, demonstrates gyroscope and accelerometer modes:
http://www.youtube.com/watch?v=xL3MbtRuTKs#!
Playing Theme from Star Trek in accelerometer mode with a previous version of the app:
http://www.youtube.com/watch?v=Z3q2uk3WZo8
Links to Google Play store:
Thanks!