BookMooch is

Here’s a Breathing Space idea worth pursuing! BookMooch is a community for exchanging used books. “BookMooch lets you give away books you no longer need in exchange for books you really want. Every time you give someone a book, you earn a point and can get any book you want from anyone else at BookMooch. Once you've read a book, you can keep it forever or put it back into BookMooch for someone else, as you wish.”

Now you have no excuse to hang on to stacks and stacks of books you’ll never touch!