A box that would create ambient music generatively, thorough algorithms and stuff. Ideally, you would have broad control, but the music would keep playing independant of you.

I think I first heard of this concept in a Brian Eno interview in Wired.

Back in the days when I used Windows, I had a free/shareware program called Soundscape that does this. You fiddle with the knobs - very easy to use - and it plays. And the music is great!

Some guys I know at our university are doing this, too, but as a multiuser project: anyone can change the settings over the Internet.

I once wrote a simple music generation program in Hypercard.

I've also patched Rosegarden to support musical transformations. A transformation is simply another piece of music, which is interpreted as a generic transformation, to be applied to the whole piece, according to generic rules. Yes, this makes sense. I never specified the exact rules, though - it was still under development.