Public Domain Images from the U.S. Government

Hey, you paid for them already! Get excellent images at:
www.archives.gov
www.digitalvaults.org
www.nsf.gov/news/mmg
www.state.gov/r/pa/ei/pix
www.nasa.gov/multimedia
http://phil.cdc.gov/Phil/home.asp
www.loc.gov/rr/print/catalog.html
www.defenselink.mil/multimedia/multimedia.aspx
www.usmint.gov/pressroom
www.nps.gov/pub_aff/imagebase.html
www.photolibrary.fema.gov/photolibrary
www.photolib.noaa.gov
www.nih.gov/about/nihphotos.htm

(Note I saw this list in FPO Magazine, a remarkable publication for magazine designers and publishers!)