Astronomy & Earth Science
EarthForce  (Learn the ins and outs of the forces of earth.)
Earth Science Enterprise  (A NASA website about the planet Earth.)
Franklin Institute Space Science Hotlist
NASA Global Change Master Directory  (Info about Earth Science: atmosphere, hydrosphere, oceans, solid earth, and biosphere.)
Ocean Planet  (A museum for the seas: images, photographs, and texts on many subjects.)
The Solar System  (An overview of the planets and moons in our solar system.)
Volcanoes: Can we predict volcanic eruptions?  (Tracking and predicting volcanic eruptions.)
Volcano World  (Educational site on volcanoes.)
Windows to the Universe


Biology
Cells Alive!  (Quill Graphics presents viruses, bacteria, and parasites in video clips.)
Charles Darwin  (Digital editions of Darwin's Origin of Species.)
Encyclopedia of Life  (Website of all 1.8 million known species.)
The Heart: An Online Exploration  
Human Anatomy Online
Seeing, Hearing, and Smelling the World (Howard Hughes Medical Institute's journey into the human nervous system.)
The Tree of Life Home Page  (Evolutionary history of living organisms.)
The Virtual Body (Explore the human brain, digestive system, heart, and skeletal system.)


Chemistry
American Chemistry Society (Chemistry links to publications, databases, education, and other related web sites.)
WebElements  (The periodic table scholar edition.)


Computer Technology
MIT's Technology Review  (Newsletter reviewing new technology and current ways technology is used in society.)
Virtual Museum of Computing's Pioneers of Computing  (Information on about 65 pioneers, plus  links to other websites.)


Ecology & Environment
Center for Alternative Technology  (Practical solutions to environmental problems.)
EnviroLink  (Online environmental resources.) 
Friends of the Earth  (A political lobbying organization dedicated to environmental advocacy and activism.)
Greenpeace  (Global organisation that influences environmental policy and promotes peace.)
Home Energy Saver
League of Conservation Voters  (Reasearch congressional representatives' and senators' position on environmental issues.)
National Aubudon Society
National Parks Conservation Association  (Action alerts on political issues and bills that have an impact on the environment.)
National Park Service  
National Resources Defense Council
National Science Foundation
National Wildlife Federation
Nuclear Control Institute  (Research and advocacy center specializing in problems with nuclear power and weapons.)


Physics
Amusement Park Physics: What are the forces behind the fun?  (Discover why amusement rides feel dangerous.) 
American Institute of Physics
Nuclear Regulatory Commission


Science Museums
The Academy of Natural Sciences
Boston Museum of Science
The Exploratorium
Franklin Institute Science Museum Hotlist
Smithsonian Institute
Natural History Museum of Los Angeles County
University of Pennsylvania Museum of Archaeology and Anthropology