So, I have been working on finding a way to listen to many of the great (and public domain) works that are floating around in PDF. After some trial and error, I have found a decent work around for IOS devices. vBookz has successfully been able to read every PDF file I have thrown at it. They also have an epub reader as well that works fairly well. The app costs $4.99, but I find it well worth it to be able to listen to just about any PDF I can throw at it.
Soon we will have a library of public domain PDF files that are readable by readers and braille software.