Came across a new service that, like BookCrossing, tries to find new homes for unwanted books. Unlike BookCrossing however, BookMooch introduces a points system and allows matching of books to individuals. Panegyrist explains the system here.
While being an improvement over BookCrossing, I don't think it solves the main problem with trading systems like these: that people will game the system by flooding it with lousy books. In BookMooch's case, since you get the same number of points when you post "MS-DOS for Dummies" as you do for Julio Cortazar's "Hopscotch", I think people will eventually start dumping books that they know are unwanted in order to earn points, so that they can ask people for books that are wanted.
Well, it's still early. Here's my list of books to give away