General Sites

• The MAD Scientist Library - Nice guide to science resources on the web.
• Science.gov - "Searches over 42 databases and over 2000 selected websites from 14 federal agencies."
• Scitable - "A free science library and personal learning tool brought to you by Nature Publishing Group."
  

Chemistry

• General Chemistry Online! - For introductory chemistry students.
• Periodic Table Live! - Interactive periodic table.
• WebElements Periodic Table - Click on an element to learn more about it.