Bookcrossing.

At the store the other day, a friend of mine found a book that wasn't for sale. The book was free, but with the requirement that the reader leave it in a public place for someone else to find when they finished. Inside the cover of the book was a tracking label, and a website address: Bookcrossing.com The website contains a "journal" for the discussion of books by people who have handled them, as well as forums, tracking tools and other services to aid the spread of public literary information.

And they say that the internet discourages serious reading. Bookcrossing.com is a wonderful application of internet-based social networking which has been applied to the world of the literati. Picture wheresgeorge.com for books.