I was thinking the other day that this would be a cool way to make money to buy more books. E-books tend to cost little, so people are more likely to buy them. You could sell them, and hopefully in enough volume to make some extra money. Then, you could use that money for books, or even trade e-books with others, for your reading pleasure. If successful, you'd have more money for other things as well, and with this site, you could find great savings for the things you want to buy with your extra money.