This Spooklight wireless turn signal and brake light for bicycles is pretty ingenious as well as useful. It works by using an accelerometer to sense your braking and with a touch panel for the turns. You recharge the thing through your computer’s USB port (you do have a computer, right?) and it will even top up your mobile phone or MP3 player in emergencies. Nice touch. £59.95.
There’s no need for batteries as its built-in Lithium polymer battery recharges through your computer’s USB port. Spooklight also works as a power bank that will top up your phone or mp3 player (and many other gadgets) out on the road. I tried it on an iPod Nano this morning and it worked beautifully. The whole kit weighs in at a featherweight 90g (3 oz).