Columbia University
Nasa: Sedac: Applications of Satellite Remote Sensing
[Free Registration/Login Required] A collection of twenty-eight data sets from SEDAC (Socioeconomic Data and Applications Center) that examine ways in which remote sensing by satellites gives us useful information about the world....
NASA
Nasa: Shuttle Radar Topography Mission
The Shuttle Radar Topography Mission, a project to collect the most accurate topographic database for the Earth, is documented at this site.