Donations to you! You would use the money however you wanted. Despite being interested in this idea for quite a while I only just recently learned of some relevant terms for this... donation voting, voting with donations, donate-to-vote. It's perhaps most commonly associated with people using donations to decide who will kiss a pig, or get a pie in the face, or get dunked into a tank of water. Sometimes zoos will use it to decide what to name an animal.
However, whenever somebody makes a donation, each dollar they donate is essentially a vote. This means that donation voting is used to rank/sort/order/prioritize all non-profits. The Red Cross, for example, receives many donation votes, which allows it to use many of society's limited resources. The Epiphyte Society, on the other hand, uses far fewer resources because it receives far fewer donation votes.
Just like non-profits, books aren't equally important/useful/necessary/beneficial/helpful. Books aren't equally deserving of our attention. Ideally we want to allocate our attention to the very best books. The challenge is that there are so many books. Therefore, ranking books should be a group endeavor. We would use our donations (to this website) in order to help allocate each other's attention to the very best books.