[arl16]

That's what I use - the Moto T505. I'm very happy with it - it works great, and the rechargeable battery is surprisingly very good. (And when I need to charge it, I just run the car charger cable up around my rear-view mirror and over to the visor, and I'm good to go - I found if you pull the unit down on the seat or center console, the FM modulator doesn't work so well.)

Otherwise, it's pretty simple. Only minor annoyance for me is if you need to switch FM channels, it takes 5-10 seconds, and finds the next best channel to use. In theory, this is great. But there's one channel that works for most of my area very well. When I've switched to go to other areas, and then come back, there's no way to go directly back to that channel. It searches around and finds a dozen other channels before getting back to the one that I want (and have a speed dial on my radio for). So it can take several minutes just to get it back where you want it.

But I've had it at tailgates, and pulled it out between a few cars, had everyone tune to the same station, and used Grooveshark for a live jukebox broadcast in stereo to everyone's cars cranked up, and it was a huge hit - very cool.