Jefferson Research Lab
http://periodic.lanl.gov
Los Alamos National Laboratory
http://www.chemicalelements.com/
An online interactive periodic table of the elements
WebElementsTM Periodic table
From David Hsu, this shows the Periodic Table of the Elements, with
a legend defining what type of element each one is. Each element leads to
an in depth discussion of it's properties.
http://www.colorado.edu/physics/2000/applets/a2.html
David Wizzy's Periodic Table