LibraryThing: Catalog your books and join the biggest online library.
From their site:
LibraryThing is an online service to help people catalog their books easily. You can access your catalog from anywhere—even on your mobile phone. Because everyone catalogs together, LibraryThing also connects people with the same books, comes up with suggestions for what to read next, and so forth.
These resources are taken from Deltina Hay’s critically acclaimed book, The Social Media Survival Guide, already in its second edition. Social Media Power readers can get a discounted copy of the book from the publisher. Learn more about Deltina and her availability for speaking engagements at Deltina.com. You may also enjoy listening to her video tutorial series on YouTube.