Project Gutenberg provide free Human-read Audio Books
The audio books are free and produced by a collaborative effort:
Thanks to AudioBooksForFree.com for our Arthur Conan Doyle series of human readings, and to LiteralSystems.org for work on new readings by volunteers. We are also working with Librivox, a similar effort to get people volunteering to read. Please consider joining them!
They are still adding new audio eBooks read by people, primarily through work by LiteralSystems.org and Librivox.
I have written a rhythmbox plugin with the aim to integrate access to the audio books into Rhythmbox.