Isle of Tune looks like Sim City. You can lay down streets like it's Sim City. But once you start planting musical trees and chime-triggering houses, you'll realize this is actually a delightful music sequencer. Suburban sprawl as symphony?
The road that you pave establishes the length of the musical sequence and how it might branch or loop. The trees and houses signify the sounds that an Isle of Tune user plants and tweaks. Once you set a car driving down the road, it starts triggering the sounds on the things it passes. The result is music.
Isle of Tune is currently available for you to tinker with on the Web, though its creators tease that it coming to iPhone, iPad and Android. They provide no release date. I went to their site and used the web version to make a song from scratch. It's tough. My song sounded worse than a car crash. Yours might be nicer.
Try Isle of Tune on the official website. Before you get started, you should know that someone made Michael Jackson's Beat It already. You can skip that song.
Isle of Tune [Official site, Thanks Matt!]