LibraryThing is a strangely addictive tool for cataloguing your books online. I'm halfway through entering my books.
The best thing about it, so far, is the tagging facility, which works in a very similar way to the tag systems at Flickr and Del.icio.us, and the fact that the entire database's tags are viewable. Here is the tag cloud for the whole site: interesting, no?
Or look here at the top 25 books and top 25 authors: unsurprisingly, J.K. Rowling is out in front, with the top 6 books (followed by Dan Brown, UGH)....but what comes after those obvious ones *is* a little surprising, to me at least. I foresee much playing, and eventually some really interesting data emerging from this.
Cataloguing my own books has been an interesting experience. I'm not at all surprised by the preponderance of novels, but that aside there is more variety than I ever would have imagined. My habit of buying books from op-shops is reflected in the number of semi-obscure novels published in the 60s and 70s. Heh heh. There are many books on or by Austen. From another point of view, I found three or four books on the weekend that I was sure I'd lost, but all along there they were sitting on the shelves. You know how you develop blind spots for book spines, particularly ones you're really looking hard to find?