General Resources
American Museum of Natural History
Cool Science for Curious Kids
Discovery Kids
Eurekalert - Current news and research
How Stuff Works

Journal of Young Investigators
Learning Channel Search
Live Science
Museum of Science and Industry (Chicago)
NASA
National Geographic
NOVA
PBS. Search "Explore by Topic
Scientific American.
Why Files

Anatomy
Atlas of Human Anatomy
Human Anatomy Online

Astronomy
NASA
NASA Kids Club
NASA Solar System Exploration
Hubble Heritage Project
Lunar and Planetary Institute
U.S. Naval Observatory

Biography (Scientists)
Gale Student Resource Center Gold (requires password from home)

Biology
BioChemNet. Some of the best biology and chemistry resources on the Internet
Biology4Kids
Biology Project

Chemistry
BioChemNet
Chem4Kids

Chemical Elements

Coral Reefs
Coral Reef Alliance
Coral Reef Protection
Hawaii Coral Reef Network
The Evergreen Project

Environmental Science

Low Impact Living  - Tips for cutting down on the use of plastics and using environmentally safe cleaning products

National Resources Defense Council 

Reduce.org - Tips to cut waste

Skin Deep - a cosmetics safety database

Meteorology
National Weather Service
Dan's Wild Wild Weather Page
Snow Crystals

Physics
Physics.org
Physics Web
Newton's Apple
Physics4Kids

Science Fairs
Science Fair Central
Exploratorium
The Franklin Institute Science Museum
Mad Scientist Network
All Science Fair Projects

Science Fairs Home Page
National Science Foundation
Science Fair Projects and Science Fairs

Zoology (Animals)
American Wildlife Resource
Alaska Zoo
Arctic Studies Center
Animal Info.
Canada's Polar Life
Enchanted Learning
National Ocean and Atmospheric Administration
Sea World
Desert Animals.com
Animal Life in Biomes
The Living Desert
Shedd Aquarium (Chicago)