Audible - Audible is the world’s largest provider of premium audiobooks and spoken word content.
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.
LibriVox - free public domain audiobooks
AlReader - Alreader.com - new perspective on reading e-books.
DigitalBook.io - Free audio books and eBooks. Search, browse, listen, read and download over 100,000 free audio books and eBooks.
Freebook Sifter - Freebook Sifter lists free eBooks from various sources.