Readers can log on to bookmooch.com and exchange used books for free, through a unique points system. Eco-Libris, at ecolibris.net, on the other hand, is a green org whereby publishers, writers, bookstores, and other organizations can balance out the paper they use in printing books, by planting trees. Because Eco-Libris and BookMooch have come together, BookMooch members can now earn points for book exchanges by planting trees with Eco-Libris. Talk about being eco-friendly!  Start getting balanced @ ecolibris.net