The project I've dreamed about for years, and is actually doable with today's technology (as compared to the time machines and space elevators) is a small desktop box with infrared scanners driven by a stepper motor. It would scan back and forth like a radar unit, looking for a heat source: the hot tip of a cigarette. Once identified, it would track that source. At a predetermined range, a small water pump (car windshield washer pump perhaps) would be activated, snuffing the cigarette, at which time it would resume scanning.

Can you tell I don't like people to smoke in my office?

Dennis