Google Play Books - Google Play Books lets you search, preview, and buy millions of books using Google Book Search.
Quickreader - Quickreader is a book reading application for the leading smartphones that is combining the solution of two main issues of the book readers namely book reader and availability of books from the leading publication houses.
Amazon Kindle - Amazon Kindle software lets you read ebooks on your Kindle, iPhone, iPad, PC, Mac, BlackBerry, and...
AlReader - Alreader.com - new perspective on reading e-books.
LibriVox - free public domain audiobooks
Freebook Sifter - Freebook Sifter lists free eBooks from various sources.