Zirconium

ChemGlobe: Zirconium - Electronic, thermal, and steric data along with an isotope table.
partisans.spurious.biz/~pkremer/projects/chemglobe/ptoe/_/40.html

ChemicalElements.com: Zirconium - Basic information, atomic structure, and isotopes.
www.chemicalelements.com/elements/zr.html

EnvironmentalChemistry.com: Zirconium - Atomic structure, chemical and physical properties, and table of nuclides.
environmentalchemistry.com/yogi/periodic/Zr.html

It's Elemental: Zirconium - Basic physical and historical information.
education.jlab.org/itselemental/ele040.html

LANL: Zirconium - History, isotopes, properties, and uses.
periodic.lanl.gov/elements/40.html

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

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

Visual Elements: Zirconium - Image, uses, physical information, and ionisation energies.
www.chemsoc.org/viselements/pages/zirconium.html

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

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