LibraryThing is a site that makes it pretty easy to make a list of all the books in your personal library. After you enter all your books, it can show you interesting statistics, such as how common or rare your books are, or which user shares the most books with you. In my case I was amused and pleased to see that the highest number of shared books belongs to Erik Naggum!
As it turns out, the creator of LibraryThing lives just a few miles from me here in Portland. Small world!