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: Make Glowing Water Without a Black Light
Presents three easy experiments where you can make water glow in the dark.
Physics Aviary
Physics Aviary: Timing Challenge
Students must show that they can successfully time an event using a hand held stopwatch.
Science is Fun
Science Is Fun: Needle Through a Balloon
In this experiment, you will learn how to push a needle right through an inflated balloon without popping it, and why this is possible.
Science is Fun
Science Is Fun: Egg in a Bottle
An air pressure experiment that shows how to get a hard-boiled egg into a glass bottle that has a mouth smaller than the width of the egg. A lit match is used in this activity.