For a taste of prog-rock inspired/inspiring nonsense, you could do a lot worse than Michael Moorcock, with particular reference to the Hawkmoon, Corum and Elric novels. The guy was an absolute legend of the fantasy scene, but tends to be overlooked for his citicism of Tolkien's Winnie-the-Pooh-esque style. If all else fails, Moorcock's the only writer I know of that collaborated on prog albums based on his characters.