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.
Bookicious - Find the best new book to read with books collections for makers, founders and entrepreneurs.
Amazon Kindle - Amazon Kindle software lets you read ebooks on your Kindle, iPhone, iPad, PC, Mac, BlackBerry, and...
Goodreads - See what your friends are reading.
LibriVox - free public domain audiobooks