USGS Urban Areas
From World Wind Wiki
The USGS Urban Areas imagery is hosted by TerraServer-USA.com. There is a lot more imagery that has been taken by USGS, but has yet to be processed by TerraServer. This is an ongoing process between the USGS and TerraServer. This list will be updated with new cities as we become aware of them.
Note: The United States Geological Survey (USGS) only takes high resolution images of United States cities. Because of this, you will only find United States cities on this list. See the FAQ for more information.