The illumi-knob is a clever, sub-$20 device that snaps onto your existing doorknob and provides a useful nighttime function:
The device uses a passive infra-red sensor to detect any movement within 10 feet and then turn on two gentle LED light rings. It's not bright enough to wake anyone, but more than enough to get you safely to - and through - the door.
The silicone rubber sleeve can be adjusted to fit most door handles and won't interfere with lock or keyhole access.
The illumi-knob runs on 3 AAA batteries and automatically turns itself off after 10 seconds if it senses no further movement.
If all goes right, the device will be available next year at Absolutely New.