I post this in the hope that some kindly (PC) developer might take on the challenge ...
I have long wanted a compositional aid that is partly algorithmic and works as follows: First, it's an algorithmic MIDI "snippet" generator. I have no idea what methods might be used. But the key is, that based on user choice, it could grow a library of snippets that can be selectively "recycled" into the composition generator. And, it would allow for user additions of MIDI snippets (e.g.: generated by other progs, or simply made by the user).
In my mind, the MIDI snippets are relatively short - a phrase, a small chord progression, a short melody, a bar of rythym. So in one sense, the program can learn the user's preferences, since you can trash or keep-and-re-include previous results. I'm sure it's a heck of a lot of work for a developer. I have a dream to code it myself but never get round to it. Besides, the only languages I know well are Visual Basic and things like PHP, and I doubt these are suitable.