Selenium

EnvironmentalChemistry.com: Selenium - Atomic structure, chemical and physical properties, and table of nuclides.
http://environmentalchemistry.com/yogi/periodic/Se.html

It's Elemental: Selenium - Basic physical and historical information.
http://education.jlab.org/itselemental/ele034.html

USGS Minerals Information: Selenium - Statistics and information on the worldwide supply, demand, and flow of the element (PDF format).
http://minerals.usgs.gov/minerals/pubs/commodity/selenium/

ChemicalElements.com: Selenium - Basic information, atomic structure, and isotopes.
http://www.chemicalelements.com/elements/se.html

Lenntech: Selenium - Physical data, chemical properties, health and environmental effects.
http://www.lenntech.com/Periodic-chart-elements/Se-en.htm

Selenium Watch - Information resource on adverse health and environmental effects from increased use of selenium by industry, maintained by a non-profit consortium of scientists, researchers and engineers.
http://www.seleniumwatch.org/

WebElements: Selenium - Extensive information on history, uses, occurrence, compounds, and properties of the element.
http://www.webelements.com/webelements/elements/text/Se/key.html

Wikipedia: Selenium - Properties of the element, including its history, applications, and characteristics.
http://en.wikipedia.org/wiki/Selenium

ChemGlobe: Selenium - Electronic, thermal, and steric data along with an isotope table.
http://partisans.spurious.biz/~pkremer/projects/chemglobe/ptoe/_/34.html

Linking Selenium Sources to Ecosystems: Local and Global Perspectives - U.S. Geological Survey materials on the environmental sources, biogeochemistry, and toxicology of selenium.
http://wwwrcamnl.wr.usgs.gov/Selenium/Index.htm

Radiochemistry of Selenium - Full text of the monograph by V. J. Molinski (Union Carbide Corporation, Mining and Metals Division, Research Center, Tuxedo, New York) and G. W. Leddicotte (Oak Ridge National Laboratory, Oak Ridge, Tennessee). [PDF] <small>(November, 1965)</small>
http://library.lanl.gov/cgi-bin/getfile?rc000058.pdf

LANL: Selenium - Production, properties, isotopes, and handling.
http://periodic.lanl.gov/elements/34.html

Visual Elements: Selenium - Image, general and physical information, source, uses, key isotopes, and ionisation energies.
http://www.chemsoc.org/viselements/pages/selenium.html