LibraryThing
I know this was a fad a few months ago, but I've just joined LibraryThing, home of the ever-brilliant UnSuggester, the lovely piece of science which tells us that people who own Kushiel's Dart are unlikely to own John Calvin's Institutes of the Christian religion.
As it turns out, typing ISBNs into the computer is more fun that it should be, and now that I have run out of books (I apparently own 201, 44 of which live in my office) I feel the need to keep going. I've made sure as many of the books as possible have the correct cover images associated with them, and even put notes on some of the obvious ones.
Fun facts: my library apparently shares two books with Tupac Shakur's and three with Thomas Jefferson's (but none with Amadeus Mozart—his are old and German anyhow). I apparently have three books autographed by the author; in order of date acquired, these would be The Elegant Universe by Brian Greene, I Sold My Soul on eBay by Hemant Mehta, and Harry Potter and the Deathly Hallows by J. K. Rowling. There are only three books which I have in common with only one other LibraryThing member; one of these is a friend who I did not know used LibraryThing but apparently took the same silly French class in college that I did. I would guess now that there are at least half a dozen books which I am the only user who has (somehow I was unsurprised I am a 1905 copy of Lanzo's Applied Mechanics or one of the Thai massage books I bought in Chiang Mai); unfortunately, while I can easily get the number of other users who have a certain book, I cannot sort my entire library by this parameter.
I also apparently have 30 unread books (or, if they are textbooks [which one rarely "reads" cover-to-cover], essentially never-been-used). I find this to be a surprisingly large nmber; I know I have a stack of about half a dozen books in my "to be read" queue (mostly new ones like Freakonomics and The Assault on Reason), but really?? Thirty?! And here I am wanting to go and buy other books? At least this will give me an excuse to start using the date started/date finished cataloging feature LibraryThing provides.
In unrelated-except-that-it's-also-on-the-internet news, I finally uploaded δ Carina to Kittenwar. She has currently won 4 battles and lost 2 ... how could someone not realize she is the cuttest kitty in all of existence?! Silly people.