[mdanger]

I looked into indoor navigation-related stuff when I was planning my senior project in college. There seems to be a problem on some university campuses where freshmen, visitors, etc. get lost easily because buildings get merged with other buildings and the university can't be bothered to renumber rooms.

I don't think indoor navigation is as big as NFC, but I can see people making at least a little bit of money at colleges (and, as someone else pointed out below, mass transit situations)