Britannica Nobel Prize: Helium
   Detailed overview and data.
   http://www.britannica.com/nobel/micro/713_23.html

ChemGlobe: Helium
   Electronic, thermal, and steric data along with basic information.
   http://partisans.spurious.biz/~pkremer/projects/chemglobe/ptoe/_/2.html

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

Corrosionsource.com: Helium
   History, sources, properties, isotopes, and uses.
   http://www.corrosionsource.com/handbook/periodic/2.htm

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

Especiál Gas Inc.: Helium
   Numeric data, uses, and general information.
   http://www.c-f-c.com/specgas_products/helium.htm

It's Elemental: Helium
   Basic physical and historical information.
   http://education.jlab.org/itselemental/ele002.html

LANL: Helium
   History, sources, properties, and uses.
   http://periodic.lanl.gov/elements/2.html

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

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

Visual Elements: Helium
   Image, animation, discovery, uses, physical information, and key isotopes.
   http://www.chemsoc.org/viselements/pages/helium.html

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