Using technology similar to an iPhone, the Spooklight relies upon a three-axis accelerator to determine when the bike is slowing down. It then displays central rear red LED brake lights to alert other road users.
Additionally you a touch sensitive pad mounted to your handle bars can be activated to show that you're turning left or right. A wireless signal is sent to the rear LED lights to blink the appropriate amber turn lights. But that's not all the 90g (3.17oz) can do. It has a couple more tricks up its sleeve.
For example, it can be used to recharge mobile phones and MP3 style music players, via a USB connectors. These receive their power top-up from the Spooklight's onboard Lithium-polymer battery, which in turn derives its energy storage from being charged from your computer (3.5 - 4 hours).
A fully energised Spooklight is said to be capable of powering the LEDs for 60 hours, though the handle bar control panel sucks them dry after about 10 hours of use.
The waterproof light (which can shine in flashes, or constantly), and the control, feature quick release fittings to they may be easily detached from the bike, if you're worried about theft.
The Spooklight sells for about £55 from its British supplier, 50 Cycles, who are happy to ship internationally. At face value it appears like a good deal. Lord knows, nighttime cyclists need all the help they can get to be seen.