A bright fellow I know recently brought Book Crossing to my attention.
Got an extra book (or seven) that you liked, but didn’t love? Print out a BCID (Book Crossing ID) sticker, and place it inside.
Leave it somewhere.
With any luck your freed novel will find its way into the world’s library, and not into some hobo’s underpants for insulation. The new owner opens the book to see the BCID sticker (which includes instructions), and logs onto BookCrossing.com to register having found the work – and to hopefully be inspired to carry on the idea.