This morning, while listening to some boring songs on C89.5, I was thinking that it would be great to have some sort of an "feedback" mechanism. Something extremely simple and dumb, that every radio should have - two buttons: a red and a green one. If you don't like the song, press the red button right now. If you like it, press the green one. That way, the station can figure out the statistics somehow and broadcast only good music.

Now, how much this should cost? Nothing for the listener, but the radio stations might pay a moderate fee to get these ratings. Eventually, loyal customers that provide lots of relevant feedback should be even awarded somehow, something similar with the "karma" concept on Shashdot.

Naturally, the technology behind must be extremely simple, cheap and accessible to anybody, otherwise radio manufacturers will resist adding this stuff in their radios. Here are some basic requirements:
- The "radio" should be able to emit data somehow, or store it for a later discharge. I don't like the idea of manually uploading the feedback data - it requires manual intervention and nobody likes that. Note that most radios today are located in cars (or so I think).
- The system should offer 100% privacy. The radio station, or any party in the middle should not be able to figure out the identity of the person sending this data. The only exception is the "feedback collection" company that owns the system.
- The system should be very secure. No third party should be able to tamper the feedback by artificially sending lots of positive or negative feedback to a certain song/program. The system should also resist to DoS attacks.

Sounds challenging... how would you implement it?