PixiTracker is a simple and fun tool to quickly create musical sketches, chiptunes and sound experiments. Without requiring a lot of musical knowledge!"
PixiTracker is also available for iOS (not sure if it's been updated with the new visualizer though).
"This was a self generating 'wind chime' patch that I was listening to for a while and thought it was pleasant enough to make a quick video out of. The trees and blue sky were recorded the day before at my folk's beach cabin.