CrunchGear: This is basically a Bluetooth speakerphone that clips to your visor and outputs sound to your car’s stereo. You can use it for calls but, even better, you can use it for audio. So if your phone or MP3 player does Bluetooth, you can stream your tunes directly to your car stereo without any wires.
Sound quality is going to be THE make-or-break feature for this device, since FM transmitting is still a little shaky. It uses a feature called “StationFinder” that supposedly finds the cleanest open FM station in your car, so hopefully it’ll put out some clean sound.