Shelfie - Get free and discounted Ebooks of your print or paper books
Goodreads - See what your friends are reading.
The Pipe - Product Hunt for eBooks
LibraryThing - A home for your books.
SWYP - Securely replaces all your cards in your wallet
Readernaut - We are a small community of readers, sharing our adventures and supporting each other as we persue a life of learning.