Just think of the next generation of radios in cars/homes that make use of digital radio with multiple streams being carried on the current single frequency allocated to a broadcaster. The broadcaster will be able to present more focused information/music/ads to the end user using digital radio--plus the larger LED readouts will also be able to provide more textual info. Who's to say that there won't also be some sort of two way communication between listener and digital stream similar to the current click throughs used by adsense--except you'd do some sort of voice recognition/audio "click" button maybe to select a topic for more info.