The socket where the cigarette lighter goes in a car. You can find just about anything that is portable can come with a cigarette lighter socket adapter to power it instead of a regular plug-in. For those things that need AC current (those that only have the regular 2-3 prong plug-ins), though, you can use a power inverter.

It is true that just about anything can be plugged into your car cigarette lighter. In fact, I recently came across a vibrator which plugged right into your handy dandy cigarette lighter. Just think of the power! I was very tempted to put in my Marky Mark "Good Vibrations" CD and take it out for a test drive. Who needs a motorcycle when you've got this??

These items are actually sold as part of a Smoker's Package in new cars now. Retails for around 50 bones, and includes metallic ashtray and lighter to fit in the socket.

I guess stock is just a socket plug and carpet in the ashtray hole...