Aluminium versus Aluminum: The different American spelling of what British English spells 'aluminium' sometimes cause puzzlement as to how it could have come about. This article tells that story.
Aluminum: Data tables and historic information.
Aluminum - Linked to Many Diseases in Humans: Provides many references on Aluminum's effect on humans and the environment.
ChemGlobe: Aluminium: Electronic, thermal, and steric data along with basic information.
ChemicalElements.com: Aluminum: Basic information, atomic structure, and table of isotopes.
It's Elemental: Aluminum: Basic physical and historical information.
LANL: Aluminum: History, sources, uses, and compounds.
Lenntech: Aluminum: Physical data, chemical properties, health and environmental effects.
USGS Minerals Information: Aluminum: Overview and a number of publications in PDF format.
Visual Elements: Aluminium: Image, animation, source, uses, key isotopes, and covalent bonds.
WebElements: Aluminum: Extensive information on history, uses, occurrence, compounds, and properties of the element.
Wikipedia: Aluminum: Details the properties of the element, including its history, applications, and characteristics.