Open, Cheap, Fast and a joy to use: LibraryThing (Score 1)

Platform: Windows, Mac, Linux -- it doesn't matter, though it helps to have a current browser. Cost: Portability: Access from anywhere you can get on the Internet (Erm, not sure about mobile devices). Share-ablility: Friends can access your book collection too if you wish. Usability: A total joy to use. I have cataloged with several systems, and I marvel at how elegantly intuitive the interface is. Type or scan an ISBN and one-click later (usually) the book is in your catalog, along with its cover, Dewey number, LoC number, all bibliographic info, a ratings system and a place for your reviews and personal subject tags (yes, color if you wish). I get a kick out of seeing my collection as a "virtual bookshelf." Community: See who else shares the books in your collection. Read other user's reviews. Add a LibraryThing widget to your blog. I can't compare it with Delicious Library because I don't have a Mac, but I can't imagine switching if I did. --A delirious customer