In an effort to bring you the most obscure technology news with some potential future military application I have stumbled across communications using ambient backscatter.
No, I don’t understand it either but watch the video
So, some clever chaps have from the University of Washington have discovered a way for electronic devices to communicate with each other without using batteries or other on board power source, instead, they use the power of other electronic emitters, TV transmitters for example.
Low bandwidth devices can be used for all manner of applications, position information, remote movement sensors, smart power grids or even simple text messaging.
Read more at Gizmag