Is there an app, or a function within an app, that will quickly provide an approximate address using GPA coordinates?

This weekend I was riding with a friend. He was struck by a car. I called 911 but not being close to home didn't know the street name. I asked someone in a passing car and they told me the wrong street name which, in turn, I relayed to the operator. Fortunately, our actual location was close to the reported one; but, (knocking on wood) if I ever need to do this again I'd like the ability to quickly get a reasonably accurate address off of my iPhone based on current GPS location.