Here are some links to interesting websites, organized by category:
PHYSICS AND ASTRONOMY
The American Institute of Physics
US National Science Laboratories (Physics-related)
National Aeronautics & Space Administration (NASA)
National Astronomy & Ionoshere Center (Arecibo Observatory)
Astronomical Society of the Pacific
European Laboratory for Particle Physics (CERN)
United Kingdom National Physical Laboratory
SCIENCE EDUCATION
National Science Teachers Association
American Association of Physics Teachers
Society of College Science Teachers
Physical Sciences Resource Center
Federal Resources for Educational Excellence
MISCELLANEOUS
Costa Rica (PowerPoint Presentation)
Public Broadcasting System (PBS)
