Portable People Meter??

http://www.arbitron.com/portable_people_meters/thesystem_ppm.htm

These little things are setting ratings of radio stations across the country, and I think they are crap. They don't account for online listeners (what advertiser wants to hear that data?). They capture incidental listening, like walking into a store or restaurant that might be playing a station you hate.

It will be the end of creative radio across America, because people don't get to tell the ratings company what they like, it's just gathering what we are subjected to.