The SpyLamp is a covert bicycle tracker disguised as a functioning tail light. Incorporating a GPS unit and a motion sensor the SpyLamp is able to detect if your bike has been stolen and send you a warning.
If the SpyLamp detects movement it will send you a text message. You can then track your bike on Google Maps and inform the police of its location.
The SpyLamp website has a demo map so you can see what the Google Map tracker looks like in practice (worryingly the demo thief seems to live just around the corner from my house).
Via: The Guardian