One of the major problems for genealogists is locating graves and sunken headstones in pioneer and abandoned cemeteries way out in the boonies. Why couldn't you hang an infrared camera of some kind on an inexpensive drone, then take it in your car and fly it over a site that looks promising? You could transmit the images to your laptop or download them when you land your drone. The graves should show up very nicely with infrared imagery. Sounds like a good market for a startup, right? C'mon, techies, let's get rolling!