Last week I picked up a book of short stories by Orson Scott Card. Two of them (so far) have inspired improvisations:
The Maker is an uptempo and very dissonant, built on augmented chords and a random alternating bassline.
Songbird is one of the most complex pieces I have improvised so far. It is harmonious (it stays diatonically in one scale almost the whole time), but there are at least three voices that I can identify. While improvising this one, I kept thinking to myself that I should end it soon before I mess up, because I can’t keep up the complexity… but I didn’t. I just kept going until the song wanted to end. In my opinion, this is one of my best improvs to date.
Oh, I should say something about “Mikal’s Songbird”. This is a jewel of Orson Scott Card’s work: great story, beautifully written, captivating to read. I highly recommend it.

Songbird is excellent, very nice.
Beautiful and very interesting.