I had an idea for scented lightbulb. I guess they would be coated with some sort of wax or something, and when you turn the light on the bulb heats and up and releases the smell. It would be nice because it would only work while you were in the area (with the lights on), and you wouldn't have to think about it, just hit the lightswitch like normal. This also has obvious implications for colored lightbulbs, with the color matching the scent.