Rocket Reads - A simpler alternative to Goodreads
Google Play Books - Google Play Books lets you search, preview, and buy millions of books using Google Book Search.
Read This Twice - Verified book recommendations from people we look up to
Amazon Kindle - Amazon Kindle software lets you read ebooks on your Kindle, iPhone, iPad, PC, Mac, BlackBerry, and...
Bookshare - I'm giving away my books
LibriVox - free public domain audiobooks