This social networking site is an interesting concept about how a book can travel from person to person. Have you every wondered who the other people are who read the book you just checked out? All you see is the the long list of return dates. Book Crossing is a site where readers can tag their books, share or "release" them so that others can read the book. Because of the tag, the next person can update the history of the book and then send it on.
While this is a fun site for adults, this could be a tremendous project for high school students. If anyone uses Book Crossing for a school, please let me know. I would suspect that kids would read many more books just so that they participate. It could also be a good summer activity using the school's summer recommended reading list.