I know I've raved about LibraryThing before, but I had to bring it up for 25 DoN because it rocks and because I just got my 3rd Early Reviewers book from them today! That's about $75 worth of books I've received and I paid a nominal fee to become a member for life. If you're a reader and you haven't already, I highly recommend checking it out. It's an excellent way to keep track of your library or books you have read. It also has message boards with (mostly) friendly posters (be careful in the "Worst Book You Ever Read" threads!), reviews, rankings, and all kind of information about a book that only a true book geek would care about.