Bookcrossing has a unique way of sharing books - it's users leave their old books on park benches, coffee shops etc. But the site itself also offers a community to discuss books, authors and characters.
Bookcrossing - share books via this famous community - register the book, and leave it to be picked up locally at a park, coffee shop or anywhere you purposely leave it. You can also hold a library of books read onsite for yourself.