I have an '04 Durango ST, pretty bare bones. In the middle of the dash, under the radio, I have a power outlet on the right (actually a cigarette lighter socket, and it turns off when ignition is turned off). It has a 3-prong socket. On the left, I have another hole that is capped, smaller in diameter than the cig lighter hole. It has a 2-prong socket plugged into the back of it with a constant 12 volts, even when car is off. What is or what can that be used for? Here's a pic:

 

My 04 slt and my friends 05 limited both have that same setup.

Did some googling, and it looks like it was originally a spot for an electronic stability control switch. The ESC was an option on a select few durangos.

 

I had the ESC on my 2007, but I can not remember where the button was located.