Boron
   Comprehensive historical data about the element and its compounds.
   http://www.du.edu/~jcalvert/phys/boron.htm

BoronWeb
   Boron chemistry and links to boron chemists around the world.
   http://www.chem.leeds.ac.uk/boronweb/

ChemGlobe: Boron
   Electronic, thermal, and steric data, along with general information.
   http://partisans.spurious.biz/~pkremer/projects/chemglobe/ptoe/_/5.html

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

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

It's Elemental: Boron
   Basic physical and historical information.
   http://education.jlab.org/itselemental/ele005.html

LANL: Boron
   History, sources, uses, and properties.
   http://periodic.lanl.gov/elements/5.html

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

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

Visual Elements: Boron
   Image, animation, source, uses, physical information, and covalent bonds.
   http://www.chemsoc.org/viselements/pages/boron.html

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