“If you love somebody, set them free.” So said the posters in the 60s. So crooned Sting in the 80s. Now Ron Hornbaker at BookCrossing.com has come up with a new twist for the 21st century: read and release. After you read a book, you leave it for someone else to find and enjoy. But, like wild birds or animals that are captured, tagged, and released, you tag your books and monitor their migration through the world. BookCrossing.com provides the labels and a place to register a book. As people find them, they are supposed to log in to the site and leave a little message.