Landsat data from USGS
As of June 4, 2007, the USGS released selected Landsat 7 image data of the United States through the Web (glovis.usgs.gov or earthexplorer.usgs.gov), high quality data with limited cloud cover.
From the USGS news release:
“This Web-enabled distribution of new and recently acquired data is a pilot project for the Landsat Data Continuity Mission (LDCM), currently projected for launch in 2011. The project will allow the Landsat data user community to help refine the distribution system planned for the upcoming LDCM. Each scene will be registered to the terrain, or ortho-rectified, prior to being placed on the Web. Copies of these data will also be available on CD or DVD at the cost of reproduction.”