Almost free books

If you've got an interest in an inexpensive source of books to read, you may want to check out FrugalReader.com. This is a service that aggregates listings of the libraries of it's members, and then allows members to request books from each other. All that's paid is postage. No membership fees. I can't see where they're making their money, but, the about page indicates an altruistic mission:

Why We're Here
FrugalReader.com exists to help you and avid readers everywhere enjoy the satisfaction and convenience of reading the books you want, when you want them, at the lowest possible cost.

Seems pretty cool.

Update: Upon further examination, it may be that part of the revenue model is click through links to Amazon to buy books that aren't available for borrowing. I certainly don't begrudge them the opportunity to make a little cash, since they appear to be charging nothing at all for the service.