JPL ASTER Gallery http://asterweb.jpl.nasa.gov/gallery.asp

NASA Earth Observatory at http://earthobservatory.nasa.gov/

NASA MODIS Gallery http://modis.gsfc.nasa.gov/gallery/

NASA Visible Earth http://visibleearth.nasa.gov/

NASA’s Gateway to Astronaut Photography http://eol.jsc.nasa.gov/

USGS Earth as Art http://eros.usgs.gov/imagegallery/

USGS Earthshots http://earthshots.usgs.gov/earthshots/

USGS Landsat State Mosaics http://eros.usgs.gov/imagegallery/landsat-state-mosaics

USGS State Shaded Relief Images http://eros.usgs.gov/imagegallery/states-ned-shaded-relief