Links:
Altair - Exploring the Electromagnetic Spectrum
Chemical Elements.com - An Interactive Periodic Table of the Elements
Conversion Factors, Material Properties and Constants
Fundamental Physical Constants from NIST
Kelvin or wavelength to RGB converter
Light and Optics online meteorology guide
Light Source Spectra Measurement Data
Personal and Historical Perspectives of Hans Bethe - Quantum Physics Made Relatively Simple
Physics.org - Your guide to physics on the internet
The American Institute of Physics -- Physics Publications and Resources
The Electromagnetic Spectrum - Index page
Thunderbolts (Electric Universe)
WebElements periodic table of the elements - the periodic table on the World-Wide Web