Normally when I read books I don't have music playing in the background as it's too distracting. But there have been occasions when (for one reason or another) I found myself reading a book and listening to music at the same time, and actually being able to concentrate on and enjoy both, particularly when the mood of the music seemed to fit the mood of the book.
It seems to me that this (with a bit of high tech magic) could be an entirely new multimedia experience - a system that plays appropriate music while you read.
It would be kind of difficult to implement, though, because everyone reads at different speeds and the speed isn't even consistent for a given person. So you'd need a computer program which can "recompose" music so that certain musical events can happen on demand. This isn't completely unheard of - I remember hearing about a roller coaster which had synchronized music which had to solve a similar problem (a roller coaster runs at different speeds depending on the mass of its payload.
Then you'd just need a system that could track your eyes to find out which bit of the book you were reading at any given moment.
Probably not possible yet but maybe in a few years.
Great idea, this really appeals to me! :-)
Perhaps there could be a touch-sensitive screen on a reading device like the Kindle, you could move your finger down to scroll to the next line, simultaneously cueing the appropriate musical score (which, in my mind's eye... er, ear... is written by John Williams).