I discovered last week LibraryThink, a really cool Web 2.0 application designed to catalog books online. It’s very easy to add book to your catalog: You just enter the title or the Author name and LibraryThink search Amazon or Library of Congress and 70 other world libraries. Once the book is found, it might be added to your catalog and tags can also be attached to it. Then you can write a review, find other people with this book in their catalog. Based on the books in your catalog, LibraryThink can also make recommendation for you. A summary of the site features is reproduced below:

• Searches Amazon, the Library of Congress and 70 other world libraries.
• Get recommendations. Connect to people with similar libraries.
• Tag your books as on Del.icio.us and Flickr (eg., wwii, Victorian, philosophy of science, vampires , theology, dogs).
• Put your books on your blog.
• Export your data. Import from almost anywhere too.
• Enter 200 books for free, as many as you like for $10 (year) or $25 (life).