I've been wasting a good part of every evening for the last couple years on Shorpy, facinating stuff.
It's really fun to try and find locations with Google Maps to compare with the old photos.
A good example is this one, I located it with nothing more than the name of the town.
Looked at an aerial view and took a guess that it would be located on a main street, found it in just a couple minutes, helped by the fact that one of the buildings was distinctive and hadn't changed much in 70 years.
Gotta love Google Maps.
http://www.shorpy.com/node/13971?size=_original#caption