My wife -bless her black little heart- gave me a helmet-mountable Hi- Def video camera for Christmas, thinking that I'd be able to make videos of my rides. However, the first thing that crossed my mind upon opening the box was, "HEY! This thing would fit perfectly on an HO gauge flat car!"
And it does.The 9v. battery powers the three white LED headlights which light up the insides of tunnels, and the camera itself also records sound. I'm now taking it around to the various layouts around here and making DVD copies of the resulting video files for the layout owners.
It's pretty neat to sit in your living room and watch a Hi-Def wide- screen recording of what your layout looks like from the cab of a loco.