Well, you’ll need a compatible “smart” device (my Motorola E815 doesn’t quite fit the bill, apparently) and
a Multi-functional Controller (MFC) from Connect2Car. This little box (pictured) connects to your car and lets you control any powered feature from the Softdash program installed on your compatible device. The Bluetooth-enabled version of the MFC will run you just shy of $600, with serial-cable and alarmed versions running cheaper and more expensive respectively.
My use for this? Freaking out neighborhood kids by turning on my key and flicking on the headlights whenever they walk by my driveway. Couple it with
my vehicle turntable
and nobody’ll ever throw eggs at my house again.