Z-boy really enjoys making compositions with this Chrome app:
It is fun, in that it involves building a system of roads, flower pots, street lights, trees, and houses, that all produce a sound (percussion or tone) when one of three cars passes by. Most of his islands sound like something Adrian Belew might cook up. They are interesting, but not particularly typically melodic. But Z ends up humming along to some of his compositions, which is cute as well as probably useful in terms of ear training.