Sulfur

ChemGlobe: Sulfur
Electronic, thermal, and steric data along with basic information.
http://partisans.spurious.biz/~pkremer/projects/chemglobe/ptoe/_/16.html

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

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

It's Elemental: Sulfur
Basic physical and historical information.
http://education.jlab.org/itselemental/ele016.html

LANL: Sulfur
History, properties, production, and uses.
http://periodic.lanl.gov/elements/16.html

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

Sulphur versus Sulfur
Some thoughts on the history of the spelling of the name of element 16: 'sulfur' vs 'sulphur'.
http://www.quinion.com/words/topicalwords/tw-sul1.htm

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

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

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

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

Radiochemistry of Sulfur
Full text of the monograph by G. W. Leddicotte (Oak Ridge National Laboratory, Oak Ridge, Tennessee). [PDF] <small>(February, 1962)</small>
http://library.lanl.gov/cgi-bin/getfile?rc000050.pdf