Non-fiction books are like a music album - 8 out of 10 of the songs I just don't want, like, or need. Why should I have to pay for the stuff I'm not interested in just to get access to the information I am?
Per-chapter and in some cases per-page purchasing of book content. Give me a TASTE of each chapter of the book, then let me decide if I want everything or just certain chapters. It's no different than what iTunes did for the music album.
Why this would be useful
Art Collecting & Study
I can only speak for myself, but in the world of art books I simply don't feel like I have the need to purchase all of an artist's content or sketchbook. In many cases I only like a selection of an artists' work. Do I really need to drop $30 or $50 just to get the 3-10 images (not even digitized ... ) in print form that I want? This same concept could also encourage numerous smaller micro-payments on something as simple as an Instagram post. Can you imagine if each time someone liked your content they were instead donating .05 to you? Maybe that's another idea altogether ...
A lot of business books fill their pages with case studies. I hate that crap. Here's a $5 book with 2 basic ideas and here's $10 of case studies proving why the 2 ideas are worthwhile. I would shoot myself if I had to listen to all these case studies on Audible. I don't care about case studies. Just give me the meat and cut the rest. It will also allow us as consumers to tell you what we really are looking for.