IBIR (In Before I-River)
Anyways.. I have the Griffin iTrip. Works pretty well as you can set it up to broadcast to any FM Station worldwide. Bound to be one that doesn't give off too bad a signal. Don't be fooled though, it will always sound like it is coming from an FM transmittter. Another downfall of the iTrip is that in order to program the device to play on whichever frequency you want, you have to load up a bunch of 'songs' that tell the device to change to whatever station. These little 'songs' are like 3 seconds of static bookended by a higher pitched beep. Not a huge deal, till you start shuffling songs across the entire iPod and you end up with a few of those in a row.
However, if you are not driving to far, you can always find a good couple of stations and just leave those frequences on there. That's what I did. Works well for me.