I have. Works great for (unabridged) audiobooks paired with their original texts. I even put on the Quake and Deus Ex soundtracks while listening to the audiobook of Masters of Doom while reading the paperback.

Hey, it worked in grade school reading groups with human-powered "text-to-speech," right? :)

Mind blown on this one too. It makes sense too - the aural bits of the brain and the reading bit of the brain don't interfere modally, so can act in parallel.