Despite the proliferation of affordable iPod-friendly car stereos, iPod FM transmitters are still a popular accessory. Nearly every iPod accessory manufacturer has its own take on the product--Belkin has its Tunebase; Griffin has the iTrip; Monster has the iCarPlay; XtremeMac has the AirPlay; Kensington has Liquid FM; and Harman Kardon has the dazzling Drive + Play 2. Digital Life Outfitters (DLO) also makes an exceptional iPod FM transmitter; unfortunately, it's not the TuneStik.
iPod FM transmitters typically come in three flavors: products that take their power from your car's cigarette lighter; products that power from replaceable batteries, and products such as the DLO TuneStik ($60) that draw power from you iPod's battery. The last of these designs are generally the least effective, lacking both the extra power and larger antenna of their kin.
Fortunately, you need to find only one dependably clear FM radio station for a product like this to be worthwhile. During our field testing of the DLO TuneStik around the San Francisco Bay Area, we were able to find just two useful FM frequencies for broadcasting, neither of which were completely free from static interference. Your results, of course, will vary depending on your location.