A breakthrough iPhone application called RjDj allows you to go about your daily business listening to the world through real-time audio effects. Similarities to drugs and to movie soundtracks are mentioned in the video, but this is much, much bigger and cooler than those. RjDj uses motion and sound sensors to layer digitally mapped feedback over everyday experience. It’s a step toward pre-processing all of the sensory stimuli flowing into your body so that they’re optimized for comfort, pleasure, and information density. I predict this is going to become one of the central uses of mobile computers, and RjDj suggests that it’s already on its way.