http://www.bookcrossing.com/home~~snip~~
Book Crossing: where 835,134 people in over 130 countries come to share their passion for books with the world. Where books take on a life of their own. How? It's easy.
BookCrossing is earth-friendly, and gives you a way to share your books, clear your shelves, and conserve precious resources at the same time. Through our own unique method of recycling reads, BookCrossers give life to books. A book registered on BookCrossing is ready for adventure.
Leave it on a park bench, a coffee shop, at a hotel on vacation. Share it with a friend or tuck it onto a bookshelf at the gym -- anywhere it might find a new reader! What happens next is up to fate, and we never know where our books might travel. Track the book's journey around the world as it is passed on from person to person.
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All you have to do is find a book you want to release, download and print a label from the Book Crossing website, and paste it in the book, then choose your place to set it free. Hopefully, it will be found by one who will read it and go to the website to post a "found" notice.
When I lived in a college town, I released a book at the local Cash Points on campus. It was discovered by a student who did go to the website and post a found notice saying that it looked interesting but she didn't think she would read it and might pass it on to her sister, so the journey ended there. On the otherhand, there are good reviews on the site and it's fun to see just where these books end up.