I've been in my house 21 years and could never figure out what a switch by the front door did. It was wired, but never did know what it controlled.
Well today I was rearranging some shelving in the garage and I came upon an outlet box with a blank cover plate. When I opened it, there were wires capped with wire nuts. I thought good, I can always use another outlet. After checking with a tester, there was no power, so I closed it up. I climbed up in the attic and tried to follow the wire, but lost it in the insulation.
It was on my mind as I was finishing up in the garage and suddenly I remembered the switch. I opened the box up again and turned on the switch and sure enough it had power.
I think the power was roughed in for another outside light.
As you can see, it doesn't take much to keep me amused.
Now if I can figure what the switch by the side door does I will be even happier. Now I know what to look for.