LibriVox - free public domain audiobooks
The Eye - The Eye is a non-profit website dedicated towards content archival and long-term preservation.
Audible - Audible is the world’s largest provider of premium audiobooks and spoken word content.
Open Culture - Discover thousands of free online courses, audio books, movies, textbooks, eBooks, language lessons, and more.
Mobilism.org - A home for book lovers, app enthusiasts, and much more.
Storynory - Storynory is another application that brings you wonderful audio stories weekly with beguiling voice of Natasha Gostwick.