iTrip Universal

Just bought one of these recently and I'm happy with it :) easy to use and the built in battery that charges via usb is simple to do.
If you need a simple way to play your mp3 players music in your car you can use this FM transmitter.
It does a fair job just remember to turn the mp3 players volume to full and back down before you use headphones. So as long as your car has a FM radio this can make your trips a bit better.
I did by a longer 3.5mm stereo plug to 3.5mm stereo plug as the included cable is very short. Being able to place it more easily the audio was clearer to. So if your car CD player doesn't have ipod support or usb this is a handy way to get around that :)

iTrip Universal