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

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

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

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

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

Lenntech: Zirconium
   Physical data, chemical properties, health and environmental effects.
   http://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).
   http://minerals.usgs.gov/minerals/pubs/commodity/zirconium/

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

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