iPhone in the Woo (1)
Just hooked a power inverter up to the cigarette lighter and mounted it behind the dash, plugged the iPhone dock into the power inverter using the included dock/power brick, and went line out on the dock to line in on the stereo. Instant iPhone integration!
Whole setup cost $150, not including the phone (it'd be $100 less if you already owned a headunit with line in). It charges the iPhone while playing music through the stereo (digitally), as well as rings through the stereo in the event of a call.