I would concentrate on micropower communications at fairly high bandwidth. Like maybe a transceiver buried in a body, using the body's galvanic electricity as the power source. Maybe using a lot of digital coding so that micropower signals can still be used to transmit data (like 100 uWatt or less level transmit power and 4 foot range).
There are a lot of biological, medical, or wearable sensor technologies that would be interested in something like that.
I think Silicon Labs makes a chip already that is heavily coded, and the coding gain allows great transmit distance for no power.