[dchest]

Think smart cards.

[dlitz]

Or RFID. If you actually want to build secure RFID devices, you need really low-power crypto.

[IheartApplesDix]

Some kind of next generation smart card, no doubt. Like a universal ID, replacement for mobile payment methods and Apple Passbook, since people don't trust their carriers to be reliable, unbiased communication networks or platforms... ah yes, I see.