ChemGlobe: Iridium
   Electronic, thermal, and steric data along with an isotope table.
   http://partisans.spurious.biz/~pkremer/projects/chemglobe/ptoe/_/77.html

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

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

It's Elemental: Iridium
   Basic physical and historical information.
   http://education.jlab.org/itselemental/ele077.html

LANL: Iridium
   History, properties, uses, and sources.
   http://periodic.lanl.gov/elements/77.html

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

Radiochemistry of Iridium
   Full text of the monograph by G. W. Leddicotte (Oak Ridge National Laboratory, Oak Ridge, Tennessee). [PDF]
   http://lib-www.lanl.gov/cgi-bin/getfile?rc000027.pdf

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

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