Kevin and I were exercising and we came up with the idea that there should be an app that will take your pdf or book and make it into a mp4 video that will scroll through your document that you want to read.  It will do it at a pace that is at your reading speed.  If enough people have read the book you could get their average read speeds for various sections and set the speed accordingly.

I just had the idea that if we had a head/iris tracker we might be able to guestimate where on the page you are at and move the page accordingly.  They have it on Galaxy S4.  However, I’d imagine that if you are walking or running basing it off of your head or iris will be difficult as your head will be bobbing.  Also, you might scroll unintentionally.