A Site I Found
You've got to check out LibraryThing. The link will take you to my library, but you can add your own, and it's free. It seems to be an interesting way to catalog your books, and use the site to find other users with similar collections. I spent about 20 minutes adding various books, but got tired after the first 100+. I plan to add all of my books to the site at some point. That is, when I'm not busy. So, look for that to be completed at some point in 2008.