Exploratorium
Exploratorium: Science Snacks: Snacks From a Z
Here is a monumental list of ideas for science fair projects and experiments, organized alphabetically. Every one of them is a link to a full page, with pictures, of information about the idea. This site is a goldmine.
Science Struck
Science Struck: 8th Grade Creative Science Fair Project Ideas
Ideas for Grade 8 science projects organized into the categories of environment, physics, chemistry, biology, animals, and astronomy.
Science Buddies
Science Buddies: Solid Motor Rocket Propulsion
What does it take to launch a satellite to explore Mars, or a mission to the moon? This project has several possible variations for exploring the physics of rockets. This is rocket science.