The following sites may be helpful. The list is not complete and inclusion on the list is not an endorsement or recommendation by the EPA.
Microscopy:
http://www.chroma.com
http://www.nikonusa.com
http://www.olympusamerica.com
http://www.zeiss.com
http://www.aqi.com
http://www.fryerco.com
http://www.fluorescence.com/tutorial/fm-optic.htm
http://www.image1.com/products/metamorph
http://www.cbi.pitt.edu/qfm/index.html
http://www.microscopyu.com/articles/fluorescence/index.html
http://micro.magnet.fsu.edu/primer/techniques
http://www.microscopy-uk.net
http://nobelprize.org/physics/educational/microscopes
http://microscope.mbl.edu/baypaul/microscope/general
Organisms:
http://www.ksu.edu/parasitology
http://megasun.bch.umontreal.ca/protists/otherprodbs.html
http://www.cdfound.to.it/HTML/khan.htm