Enter what you’re reading or your whole library—it’s an easy, library-quality catalog. Because everyone else is doing it too, LibraryThing connects you with people who read the same things.
Source: LibraryThing | Catalog your books online
(aside: This Windows Live Writer thing is awesome. I just used it for the first time to begin blogging an item I just found (ie Library Thing, above), and it automatically “blockquote tags” the part that I highlighted on the page. Another step I previously had to do manually is eliminated. More on Live Writer in a sec……)
Library Thing has begun to appear in a few places and blogs I browse regularly. Quite the interesting undertaking.