book mooch

I don't know if any of you have heard of this before, but there is a great place online to swap books. You set up an account with bookmooch.com and then you get points to get books. It is an interesting little system. It is free in the sense that you pay nothing for the books - but you have to be willing to share your books and pay for shipping to whoever it is that wants your books (so there is the "hidden" cost). So you only get books when you send books... sounds complicated but they've explained it really well on their site.

From their site...
In order to mooch books from others, you need to earn points which you use up as you get free books from other people.
You earn points when you:

Type books in: enter books you own and want to give away. Each book typed in gets you 1/10th of a point.
Give books away: respond to a mooch request, and send your book to them. 1 point awarded, 3 points if sent to another country.
Acknowledge Receipt: after you receive a book, leave feedback for the sender and earn 1/10th of a point.
You use up points when:
Mooching Books: each book you receive costs you 1 point, 2 points if it was postal mailed from another country.
Charities: you can give your points to worthwhile charities we work with.

Some additional facts:
2:1 ratio: you have to send out at least 1 book for every 2 you receive. If you don't keep this ratio up, you won't be able to mooch any books, even if you have the points, until you improve your ratio. Sending internationally counts as 3 books.
Feedback score: if your feedback score is bad, people may refuse your mooch requests. Efficient response and well-packaged books in good condition earn good feedback points.
Lost in the mail: if a book is "lost in the mail" the sender gets their point anyway, and the receiver doesn't lose a point. You're allowed a limited number of "books lost in the mail" in order for us to limit possible fraud.