NARA AND USGS for preservation of EROS Data

See more on this, http://www.gcn.com/online/vol1_no1/46481-1.html?topic=&CMP=OTC-RSS#
"The National Archives and Records Administration (NARA) and the USGS have signed an agreement to ensure preservation of and access to Earth Imagery and geospatial data currently archived by USGS at its Earth Resources Observation and Science Center in Sioux Falls, SD. The records will remain at the EROS Center under the day-to-day control of USGS..." (source, govdoc-l)

USGS SPOT Images

Are you looking for SPOT Images? The full archive of historical Landsat 7 ETM+ data from the USGS, wherein users pay for on-demand processing to various parameters before , will be free to downloading. See more in detail at
http://landsat.usgs.gov/images/squares/USGS_Landsat_Imagery_Release.pdf