"Book-sharing" service/Individual book collections online

For books there is already a Mac program, Delicious Library, which lets you (or your maid) walk round the shelves with a barcode reader, scanning in the codes on modern books, and then collecting the information about them from Amazon. But these programs, however glossy, are somewhat narcissistic. They miss the social strengths of internet collections: the ability to advertise your own good, or at least distinctive, taste, and find other people whose tastes overlap with yours. One of Amazon's great innovations was to suggest books based on what like-minded people had bought. The technique has been refined in Flickr, the photo-sharing service, where the people who share your tastes are identifiable individuals, and so are their friends, and the friends of their friends.

Now this model has finally been applied to books. Librarything.com has been built by Tim Spalding, a freelance web designer in Maine with a classics degree and an interesting taste in books. It's free for small collections (up to 200 books) and USD10, for life, for anything more than that. Last week, word of it got out on a couple of blogs, and Spalding went from fewer than 5,000 books registered to more than 20,000 - the second 10,000 went on in less than 48 hours. I think this might be going to take off in a big way, and if Spalding doesn't make a fortune from it, somebody else surely will.