‘Mutewatch is a silent alarm in the shape of a vibrating wristband. This discreet device with its disguised touch screen brings structure and time back to its user. It serves as a quiet reminder that helps you to follow your own agenda without disturbing people in your surroundings.’

http://www.mutewatch.com/
http://www.mutewatch.com/
http://www.mutewatch.com/

I never wear a watch but now I clearly need one.