There is at least one community that does (properly) free audiobooks: LibriVox. However, they are restricted to public domain works, so their catalog is restricted (it consists mostly of old works that have gone out of copyright).

They have a fairly large number of audiobooks categorised as non-fiction (although the bible appears to be put in this category). Also, the free restriction means that modern/up-to-date courses are likely to be hard to come by (that said, I don't really know that much about LibriVox's catalog, and I'd be very happy to be proved wrong).