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.