European car safety researchers have developed a camera-based system that watches your facial expressions while you drive, and then uses highly accurate emotion detection algorithms to work out when you're suffering from road rage. The idea behind this system is that, when you're irritated or angry, you become a more aggressive driver and less attentive -- leading to more accidents. The same technology can also be used to measure tiredness and fatigue, by measuring the percentage of your eyelid closure, and then warning you to take a break before you fall asleep at the wheel.