Next Generation mobile personal radio

What if you attached a gizmo to your ipod that lets you broadcast the music you are listening to onto any available wifi network. then anyone else on either a laptop or an ipod can tap into your personal radio station to listen to the music. If they like what they are hearing, they can dowload it onto their device and (maybe) pay for the music. That way you have a constant stream of personal music ready for your dabbling and experiencing. It takes the p2p concept and makes it mobile. It also takes music and moves it out of "places", like the home, a club and really makes it everpresent. Obviously some challenges with having it be on a wifi network, since the coverage is limited but maybe that is ok. How could you extend this concept thinking of the ipod as a mobile information collection device. Maybe one business model in lieu of paying for the music is that you have listeners hear and ad - for each ad they hear, they get 1 song, or something like that. An alternate business model.