LibriVox - free public domain audiobooks
DuoBook - Easily switch between reading and listening to your favorite books.
Audible - Audible is the world’s largest provider of premium audiobooks and spoken word content.
Pocket Listen - Reading is hard. Listen to articles instead.
Mobilism.org - A home for book lovers, app enthusiasts, and much more.
Audiobook Player - An audiobook player using an embedded Microsoft mediaplayer