From Ars Technica: "Random House is... experimenting instead with selling books the iTunes way, in bite-sized chunks; no longer will you need to purchase that Complete Guide to Astrology when all you really care about is Scorpio."
That's not a bad idea. I could imagine buying chapters of books for research purposes. It would also be really useful for textbooks, especially in classes where I don't really need them. I could just buy the questions required as homework. Textbook publishers won't do that though.