https://www.auralfractals.net

"Aural is a fractal music generator that creates endless musical themes from Chaos. You can generate an infinite amount of fractal compositions in Aural and export them as MIDI files, so you can use them in your favorite music composer software."

Not exactly AI, but advanced mathematical generators. We all know the spiffy graphic art you can get from fractals, this does something like that with music.

Here's a piece I generated using the "Cellular Automata" preset, whatever that means and whatever exactly it did. I asked for 10 minutes of raw MIDI material then cooked it all up in Logic. I find the melodies and harmonies I was given eerily beautiful, and I'm happy with the way I rendered them.

https://soundcloud.com/mark_hayes/cellular-automata

It is exactly 10 minutes long and the listener might be forgiven for not staying for the whole thing, though there are some surprises that reward patience (storm of glass marbles!) and it wouldn't be the worst way you could spend the time.