I just completed my prototype of suggestion #5. I used my arduino PWM output to control an LED. I hacked one of the airwick motion sensors and connected to my arduino. When there is no motion, it dims the LED to a minimum level. If someone walks in the room, it ramps up to full brightness. After about 20 seconds, it ramps back down to the minimum level.This is great for a bathroom or someplace you would want to go to late at night, but don't want to be blinded by turning on a light switch. I plan to post an instructable soon.