Collaborative Composition Jukebox

This is a smallish weatherproof and vandal-proof machine, of bronze or brushed aluminum, that sits in a public park or plaza. It has only a few controls, all clearly marked with ideograms that even a child can learn to understand. One button starts the machine playing, another switches to the next composition in the queue, and there are buttons for deleting or adding a musical phrase inside a composition. If the machine has not played in an hour or so, it will begin to play all by itself, hoping that someone will notice. Oh, and there's a replay button for restarting the current composition.

The machine has a scaled-down midi orchestra (piano, drums, orchestral harp or classical guitar, bass, a few other things) with *good* sound patches, and it saves compositions to an internal database (the queue). Musical phrases are composed algorithmically (there are lots of programs that do this already) in appropriate key, meter, and tempo for the composition at hand. All the user does is select phrases which sound good to him or her. This puts a form of found composition out where kids and casual passersby and anyone at all can tinker with it. (There are already plenty of ways for the PC-literate do this kind of thing at home.)