SleepSmart is a kind of clock that measures your sleep cycle and waits for you to be in your lightest phase of sleep before rousing you, making it more likely that you wake up perky.

SleepSmart records the pattern of brain waves produced during each phase of sleep, via a headband equipped with electrodes and a microprocessor. This electrical activity is communicated wirelessly to a clock unit near the bed. You program the clock with the latest time at which you want to be wakened, and it then duly wakes you during the last light sleep phase before that.

The concept was invented by a group of students at Brown University in Rhode Island who, with help from entrepreneurial grants and alumni investors, have almost finished a prototype and plan to market the product by next year.

Via New Scientist.
Check also SleepWatcher that wakes you up while at the lightest part of your sleep cycle as well.
Other fav’ alarm clocks: the one that hides, the one that drags you out of bed, the teddy bear-activated one.