And Wikipedia has this: 'BookMooch is a non-commercial site, not charging any membership or use fees. Some revenue is generated from commission when users purchase a book from Amazon.com through referral by the site, but the founder has stated that there is no need for BookMooch to generate profit, and refers to this income from Amazon as "making money by accident." Running expenses are covered by Amazon commissions ... for approximately every 100 books mooched, one book is purchased from Amazon.com ...'
BookMooch is a service that lets people trade their used books. Though BookMooch is free to members, the site generates an estimated half-million dollars in annual book sales for Amazon because of a browser plug-in called the Moochbar, which matches members' book wish lists to Amazon's retail inventory.
'BookMooch allows its users to exchange books using a points system. Members earn points by adding books to their inventories, by sending books to other members and by providing feedback when they receive books. The points earned can then be used to "buy" books from other members. All books "cost" the same number of points, with a multiple point surcharge for
international mooch.' Wikipedia.
At Silverfish Books we have our own mooching service (had it for more than a year now). Readers can drop off books they no longer want to own, to give them away to others. We call it a book adoption service and encourage those who adopt a book to drop a thank you note to the previous owner.