Old S.F. is an application which displays historical photographs in the San Francisco Bay area over a Google Maps basemap. The developers (who can be followed on Twitter: @danvdk and @ravejk) geocoded thousands of images based on the subject of respective photographs in addition to cross streets in the images. According to the site, the developers have geocoded 13,000 out of 20,000 photographs, found in the San Francsico Historical Photograph Collection, that have information regarding location.