One of the best book-sites around celebrates its first birthday today - congratulations, LibraryThing! In just a year, the site has grown from scratch to a community of over 73,000 members, who have cataloged nearly 5.2 million books. If you're not addicted to LT yet, go there and play around for a half hour or so ... it'll grab you!
I must note too that yesterday I had my first out-of-the-blue real-world encounter with another LT user, who came into the shop having seen my recommendation of it in a forum post. What fun!