Images of Nature
http://ion.eas.asu.edu/index.html

University of Leeds-School of Earth Sciences-Dr. Kurt Konhauser
http://earth.leeds.ac.uk/~kurt/konhause.htm

Nanoworld-The University of Queensland
http://www.uq.edu.au/nanoworld/images_1.html

CosmicLight.com
http://www.cosmiclight.com

ICTVdB-Virus Databases Online-Columbia University
www.ncbi.nlm.nih.gov/ICTVdb/

American Society For Microbiology Digital Image Collection
http://www.microbelibrary.org