I've considered using thematically appropriate music in my campaigns before. I'm a big fan of Two Steps From Hell, and their music is very good for epic battles. Unfortunately, one of my more stubborn players usually vetoes the idea, seeing it as distracting.
I did have some success using the sound of the T-Rex in Jurassic Park as a dragon roar, though. As the players were level one at the time, it scared the crap out of them.
