ChemGlobe: Silicon
   Electronic, thermal, and steric data along with basic information.
   http://partisans.spurious.biz/~pkremer/projects/chemglobe/ptoe/_/14.html

ChemicalElements.com: Silicon
   Basic information, atomic structure, and table of isotopes.
   http://www.chemicalelements.com/elements/si.html

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

It's Elemental: Silicon
   Basic physical and historical information.
   http://education.jlab.org/itselemental/ele014.html

LANL: Silicon
   History, sources, uses, and properties.
   http://periodic.lanl.gov/elements/14.html

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

Radiochemistry of Silicon
   Full text of the monograph by David R. Schink (Isotopes, a Teledyne Company, Palo Alto, California). [PDF]
   http://lib-www.lanl.gov/cgi-bin/getfile?rc000059.pdf

Silicon Chemistry Primer
   Review of silicon and silicone chemistry including properties and types of materials that can be made.
   http://www.dowcorning.com/content/about/aboutehs/ehssiliconchemistry.asp

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

Visual Elements: Silicon
   General and physical information, source, uses, biological role, key isotopes, and ionisation energies.
   http://www.chemsoc.org/viselements/pages/silicon.html

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