ChemGlobe: Iron - Electronic, thermal, and steric data along with an isotope table. - http://partisans.spurious.biz/~pkremer/projects/chemglobe/ptoe/_/26.html
LANL: Iron - History, sources, uses, and properties. - http://periodic.lanl.gov/elements/26.html
Wikipedia: Iron - Properties of the element, including its history, applications, and characteristics. - http://en.wikipedia.org/wiki/Iron
Lenntech: Iron - Physical data, chemical properties, health and environmental effects. - http://www.lenntech.com/Periodic-chart-elements/Fe-en.htm
EnvironmentalChemistry.com: Iron - Atomic structure, chemical and physical properties, and table of nuclides. - http://environmentalchemistry.com/yogi/periodic/Fe.html
Visual Elements: Iron - Image, general and physical information, source, uses, key isotopes, and ionisation energies. - http://www.chemsoc.org/viselements/pages/iron.html
USGS Minerals Information: Iron - Statistics and information on the worldwide supply, demand, and flow of the element (PDF format). - http://minerals.usgs.gov/minerals/pubs/commodity/iron_&_steel/
ChemicalElements.com: Iron - Basic information, atomic structure, and isotopes. - http://www.chemicalelements.com/elements/fe.html
It's Elemental: Iron - Basic physical and historical information. - http://education.jlab.org/itselemental/ele026.html
Radiochemistry of Iron - Full text of the monograph by J. M. Nielsen (Hanford Laboratories, Hanford Atomic Products Operation, Richland, Washington). [PDF] - http://lib-www.lanl.gov/cgi-bin/getfile?rc000015.pdf