Google Street View is impressive enough but how about linking old photographs to current maps? See the results for New York City here.

Having spent some time in suburban archives, there are plenty of old photographs ready to be matched to current maps. However, I imagine there are at least two major hurdles: (1) finding the hours to collect the photos and do the work (the photos exist in in numerous locations) and (2) how the work could pay off (New York City is a place of interest but what about every Main Street in America)