If you were in a room with 3 switches that turn on 3 bulbs on the other side of the room, but you could only exit through the door to the other room ONE TIME, how would you be able to find which switch belongs to which bulb.
This is a pretty old riddle, so I can't claim that my solution is original. Anyway, here is how you do this.
First, you turn on one of the switches and you leave it on for like 10 minutes. When the 10 minutes are about done, turn a second switch on for 30 seconds or so. Then turn those two switches back off. Now you go into the other room and you feel the light bulbs. The hot one is controlled by the first switch. The warm one was only on a few seconds so it's controlled by the second switch. The one that is completely cold is controlled the third switch, the one you didn't turn on.
Of course, if the people are "green" and use the compact flourescent bulbs, this isn't going to work...