A blogpost from LibraryCrunch listing great additions to the library catalog of the future.

You can look at what various people and groups of people are reading on the web here. You can get an account and add your own links, and create and join groups here too. If you get an account, or create a group, either one can be made private, so nobody but you (if a private account) or your fellow group members (if a private group) can see your links.

Web application LibraryThing lets you catalog all the books you own and use tags to organize your collection.
Add book titles by entering a title and viewing search results from the Library of Congress or Amazon. LibraryThing adds the book’s card to your catalog with ISBN, publisher, year and an image of the book cover. You have space to add a book summary, tags, your comments and a review. See what other users also have each book in their library and what they’ve tagged it. LibraryThing is an impressive cataloging app that feels like del.icio.us for books.