If you're a book lover, Library Thing is a useful tool to help you catalog your books online, write and read book reviews, see what other people like you may be reading and participate in book discussion threads. In a matter of a few minutes you can add books to your online catalog, tag 'em, and rate them using a star system. Based on your selections, you can then see who else shares your excellent taste in their own book arsenals. Think Facebook for books.

You can catalog up to 200 books for free and if you go beyond that you can get a paid account for $10 per year or $25 for a lifetime membership. There's a little widget you can add to your blog, if you wish, which shows visitors what you're reading. Library Thing is currently beta-testing LiveJournal and MySpace widgets.

Some other nice features include:

• Import data from files and web pages. Supports Delicious Library, BookCollector, Amazon Wishlists.
• Export all records as tab delimited text.
• Mobile look-up - http://www.librarything.com/m/