I'm looking at how RFID technology is now using sensors to transfer/stream data.
NFC, if i'm correct is essentially an evolution of RFID. It transmits data to trigger a configured set of events (in the case of Mobile, usually as a catalyst for and ID establisher for bluetooth/wireless comms)
Amazing potential to use current RFID - sensor input embedded in theother half to pick up heartrate, temp, humidity, or replace sensors with embedded data or information. include a usb connection to load that info and you have a fully replaceable data store and management solution that you could swap between handsets.
One back with all your work stuff on it and at the end of the day, swap it over for all your movies and music on the trip home.