http://www.wikipedia.org/wiki/Discovery_of_the_chemical_elements - Properties of each of the elements, with information about their discovery.

http://allperiodictables.com/ClientPages/AAEpages/apt_3_History.html - A brief history of the periodic table.

http://www.chemsoc.org/viselements/pages/history.html - An extensive history of the periodic table.

http://genesismission.jpl.nasa.gov/ - The Education area of this web site for the Genesis mission contains a number of classroom materials on the periodic table and cosmic chemistry.

The Big Bang and Early Nucleosynthesis

http://wmap.gsfc.nasa.gov/ - The "Universe" section of this site for the Wilkinson Microwave Anisotropy Probe provides information on the Big Bang and nucleosynthesis

Spectra of Atoms

http://home.achilles.net/~jtalbot/data/elements/ - Emission line spectra of a wide range of atoms.

Life Cycles of Stars

http://imagine.gsfc.nasa.gov/docs/teachers/lifecycles/stars.html

Cosmic Evolution from the Big Bang to Human Kind

http://www.tufts.edu/as/wright_center/cosmic_evolution

Cosmic Rays

http://helios.gsfc.nasa.gov/

"Tabling the Matter" by Jim Caddick, The Exploratorium Quarterly, Summer 1992.
Mendeleev and the development of the periodic table.