I'm going to be visiting a distant city in a few months, and want to start making plans with people I know there, some of whom I don't keep in touch with as regularly as perhaps one ought to. The major social networks have locations (and particularly, current residence) in peoples' profiles, but don't seem to have any search functionality coupled to that. When I search for a city on Google+, I find everyone I know who's ever lived there.
How can I do a search of "people I know living in city X"? I'm open to external utilities that hook into the sites' data, if that's the only way to do it.