The MIT Media Lab has recently developed metallic temporary tattoos which can communicate with other electronic devices such as sending signals to your mobile phone.
They call it DuoSkin. It already has some technology experts quite excited at the possibilities of using your own skin as a track pad for mobile applications or a remote sensor (for unlocking doors).
What about GPS individual tattoos that you can track a person….When is that comming?
…and that would be the dystopian sci-fi application for this technology.