MyBikeNumber is a new startup which is aiming to offer an international bike registration system. The hope being that if a bike is stolen then it can be tracked across more countries. It is available for anyone to register their bike for free. In your listing you add pictures, your frame number and your bike components.
When your bike is added to the database you then get a unique code which you can affix to the frame. This can then be scanned. There is also the option to search for unique codes to check whether the bike you are about to purchase is stolen.
The concept is impressive and no doubt relies on a large number of cyclists to register their bike. If it catches on then it will be an effective deterrent against theft.