LibraryThing, as you might have guessed, is a project that has to do with reading. It is as simple as a good idea can get: share what you read. Share it with others, but also - share it with yourself. By creating a virtual library of your own books, you enter the realm of infinite connections and marvelous adventures. Well, you get the picture. You organize your books, tag them, describe them, and, above all, see what you've been missing. You can see who else owns these titles and what else they own, and thus start jumping from one tree to another... Of course, you can rate them and compare your ratings with others. Of course, if you don't like the Web 2.0 idea of communication network, you can have a private library and forget all the rest. And what's really pretty, and I mean real nice, is that you just type a tiny bit of info, and the rest is filled in automatically through one of the nearly 50 libraries its connected to worldwide(among them, the Library of Congress). If you can't find it - you can always import it, say, scanning the image and putting in the data.
I see one downside: language. Having books in several languages, I find it difficult to share and follow only the books printed in English. There has been a surge in French books (thanks to some positive internet press in France), but all this is just painfully slow. Once again, it somehow feels as if the world was English, and the rest was an appendix (one Polish library, none in Portuguese...). Then again, if the rest of the world simply doesn't make all these great sites... Then again, if they did, how would I know about it? (see the geographical location of LibraryThing users here.
This is a very young initiative (started less than a year ago). It has relatively few books on art. We could start changing that.
Signing up is just unbelievably easy. Just write your username and a password, and you're in. My mini-test-catalogue is here. If you want to catalog over 200 books, it costs $10 (for a year) or $25 (lifetime). Methinks: yay.