There was a previous thread about writing tunes, which gave one method as starting from a known tune and then progressively altering the notes (and presumably the timing) so that the end result is a new and different tune. I haven't tried it yet (at least not knowingly....) - but it sounds like a cunning plan.
That sounds like one where you'd be working it out on paper as you went along.
I wonder if you could come up with a transformation algorithm that you could run against a whole load of tunes to automatically generate new ones. That doesn't sound terribly muse-ish though does it? So would it still be 'Art' ???