Here are some links that you may find useful
Radioactive
 Nuclear Radiation Websites
NASA
 National Aeronautic and Space Administration Website
Subduction
 US Geological Survey Website
ChemSoc
 Visual Periodic Table from the Chemical Society Network (it takes a while to load and requires flash)
Discovery Channel
 The Discovery Channel Website
Windows to the Universe
 Windows to the Universe - Info. on Earth and space science
Periodic Table Periodic Table of the Elements Websites
Electromagnetic Spectrum Electromagnetic Spectrum from NASA's Imagine the Universe