Most data sets are for sale but the site includes clickable demonstration maps.
Prepared by the US Geological Survey, these satellite images portray the dramatic environmental changes around the city of Beijing between 1976 and 1991. A rich resource for historical, social and natural science data on China within a geographic information system. Includes interactive maps. MapQuest has zoomable maps. The map of Beijing zooms all the way down to 100 meter sections of the city.