I’ve had mostly good experiences with products from XtremeMac (even though none of them have ever actually been used with a Mac). The first iPod case I bought from them was great, ditto for their HDMI switcher. I also liked the design and features of the Luna Voyager alarm clock dock, but had found it difficult to get certain devices to fit in their dock adapters and the dock adapters themselves very difficult to remove. Plus, I had to jump through hoops to get a digital copy of the manual. (When repeated e-mail exchanges proved fruitless, I picked up the phone and talked to a person who resolved it within five minutes.)
Those who have an older car or one without a Bluetooth, though, may want to take a gander at their recently announced InCharge Auto BT. (The company also produces a version for the home using standard AC outlets.) While there have been countless products over the years to send music from a cell phone (or just about anything else) via local FM transmission, the result is often terrible in cities with many FM broadcasters. In contrast, the clever XTremeMac approach acts like a standard USB charge for a smartphone, but integrates Bluetooth reception and a cable to connect to any car head unit that has an aux jack.
I suppose this begs the question, “Why do you need Bluetooth?” You could just charge the phone and run a cable from its headphone jack to the AUX jack. For one, this approach should prove a little neater with a shorter cable and provide for more flexibility in terms of where the phone is placed in the vehicle. On the other hand, if you’re not above doing a little installation work in your dashboard (or paying for it) you might just want to start anew with a car stereo that has built-in Bluetooth.