Best. Modulator. Ever.

FM transmitters are the easiest way to connect an iPod to your car stereo - especially if you don't have an aux in or tape player like me. I've tried a few different models including the iTrip and the Monster iCarPlay; they work but the sound quality is sometimes "eh" and suffers from interference. I recently picked up a Kensington Digital FM Transmitter and it is a huge improvement. Almost no interference and the audio is loud and clear. It will tune to nearly any FM channel (although not 87.9, which is clear throughout most of the US) and is very easy to use with a bright, backlit LCD display indicating the frequency and 3 programmable presets.

Update: To tune to 87.9, hold down the two rightmost preset buttons. The tuning will then scroll past 107.9 and start over at 87.5, allowing you to tune to 87.9. I have no idea why this is "hidden" but it works. Sadly, it resets to 107.9 when you turn off the car, and you can't set a preset for 87.9, but it does work and the sound quality is awesome for an FM transmitter.