"Jay Honeck"
With the advent of laptops and portable DVD/CD players, it would seem
logical to have some sort of a power port in the back seat -- yet I have
never seen one.

I have one cigarette lighter plug in the panel beneath the control
column of the pilot's yoke, which I use to power a GPS. There is
another sidewall mounted cigarette lighter plug behind the pilot's
seat, where the passenger can plug in. I use this to power a CD
player then connect the audio out into a music jack for my PS
Engineering intercom. The plane is a C310K. Both plugs are original
factory items.

Brian