I have recently discovered a site called Librivox, which is the audio book equivalent of Project Gutenberg. Their goal is to produce audio files for every book in the public domain. I enjoy listening to audio books very much but don't buy them because they're so much more expensive than print books (or e-books). You can check out audio books from the library, but here is one more free option.
http://www.librivox.orgDownsides are that all of the books are read by volunteers so the quality is a bit uneven, and one book with many chapters is typically read by multiple people. Sometimes the reader is easy on the ears, other times not so much. Still, there are some books that aren't available otherwise.
Enjoy!
