[hot_pastrami]

Well, ok... here's an easier one in the meantime. This one works better when asked verbally, because it's cool to watch how long it takes someone to think of a solution:

There are three light bulbs in a room with no windows, and a closed door. In front of you are three on-off switches. You know that each switch controls one of the light bulbs inside the room, but you don't know which switch matches which bulb, and they are not wired in any particular order.

Your job is to match each switch to it's bulb. You may only enter the room once, and you may not leave the door open. How do you accomplish your task?

I heard this one from a client of mine... he's a site manager for a Microsoft call center. Apparently, this is one of the questions an interviewer at Microsoft will ask potential employees during an interview, to test their reasoning skills.

He told me about how he was sitting in a management meeting at Microsoft with about twenty other managers when someone posed this very question of the group... he bragged that he was he only one to come up with the answer, and it only took him about twenty minutes. So he put the riddle to my friend and I, and I figured it out almost immediately. I think I stole the pride he'd had in answering it in "only" twenty minutes. Heheh.

Incidentally, my friend later came up with a different answer than I did, which is still a valid solution, but not nearly as elegant.

Edit: I added "on-off" to the description of the switches, to clarify the fact that you know which position will turn the bulb on, and which will turn it off.