Beryllium: Data tables and historic information.
ChemGlobe: Beryllium: Electronic, thermal, and steric data along with basic information.
ChemicalElements.com: Beryllium: Basic information, atomic structure, and table of isotopes.
EnvironmentalChemistry.com: Beryllium: Atomic structure, chemical and physical properties, and table of nuclides.
It's Elemental: Beryllium: Basic physical and historical information.
LANL: Beryllium: Sources, properties, uses, and handling.
Lenntech: Beryllium: Physical data, chemical properties, health and environmental effects.
Peter Clerkin's - Beryllium: Some information about the element.
Radiochemistry of Beryllium: Full text of the monograph by A. W. Fairhall (Dept. of Chemistry, University of Washington, Seattle, Washington). [PDF]
USGS Minerals Information: Beryllium: Statistics and information on the worldwide supply, demand, and flow of beryllium.
Visual Elements: Beryllium: Image, discovery, uses, physical information, and key isotopes.
WebElements: Beryllium: Extensive information on history, uses, occurrence, compounds, and properties of the element.
Wikipedia: Beryllium: Properties of the element, including its history, applications, and charateristics.