BookBuddy - Kimico is a software development company focused on bringing you Essential iPhone and iPad apps designed to keep you organized.
Goodreads - See what your friends are reading.
LibraryThing - A home for your books.
Tellico - Tellico is a KDE application for organizing your collections.
BookAuthority - BookAuthority collects the most recommended books on business, technology and science - as featured on CNN, Inc and Forbes
inventaire.io - Keep an inventory of your books. Share it with others. Discover the books available in your network!