Time Shutter is another great Google Maps based website that allows people to see how cities used to look and how they have changed. Users can upload historical images to the site and browse through the images submitted by others.
Currently the site is concentrating on historical images of San Francisco but images for New York will also soon be added. The site includes many postcards of San Francisco from around 1900 and includes a historical map overlay featuring the Chevalier Commercial, Pictorial and Tourist Map of San Francisco from 1903.
Time Shutter is also available as a free iPhone application.