Our gadgetry bretheren at Gizmodo offer up a device to combat sleep-driving, a bracelet that will let a driver know when he's too fatigued to drive. It interacts with an RFID tag that's mounted inside a car to somehow detect whether the driver's tired. No word on whether it can tell if he's been dancing with Mr. Ambien or not.
Driver Fatigue Bracelet [Gizmodo]
Saab Develops Breathalizer Key [internal]