History of chemistry
A series of papers on the history of chemistry arranged by topic that lists the individual contributions of important chemists

Web Elements
An interactive Periodic Table that lists just about any property that you can imagine about an element

Fundamental physical constants
A table of the most important physical constants used in general chemistry & physics

Unit conversions calculator
An online calculator that will allow you to interconvert measurements between different units

Materials safety databases
The most comprehensive site for searching public MSDS sheets for safety information about manufactured chemicals

Nobel prizes in chemistry
A list of the Nobel prize winners in chemistry with links to their biographies and other items relating to their work