The following tip comes from Scott Leavitt of Oakley Signs:
Are you getting ready to move but have a stack (or two or twenty) of books to clear out? Here’s a novel idea (excuse the pun!):, the first “read and release” book recycling website,  allows you to take books you are willing to part with and share them with others all over the world.
The process is simple: Register for a free account on the website, tag your “free book” with a BookCrossing ID number (BCID), then leave it in a public place. As your book travels the world (so far,  it’s in 130 countries), other people log in to BookCrossing and update where the book was read. It’s a fun way to promote book re-use and connect with other readers.