Bill Nye Home Demos includes 40 certified experiments from acid attack, burn rubber to temperature time warp and many others.  You will need the plug-in, Shockwave to use this site. 

Edible/Inedible Experiments Archive

This site includes a "series of experiments demonstrating concepts in different branches of science.  Some may be eaten before, during, or after the experiment, and some definitely should not be eaten at all."

Fun Science Gallery

"Fun Science Gallery is the site for the amateur scientist.  Here you will find instructions showing how to build scientific equipment from relatively cheap materials.  Projects include instructions for making telescopes, microscopes, batteries, sidereal indicators, and several other instruments."

Quick and Easy Activities

Quick and Easy Activities is a directory of activities for pre-school, early elementary, later elementary, middle school, and high school.  Here you can explore crystals, dancing pennies, density, movement, and much more.

Science Snacks Online

Science Snacks Online are mini-science experiments divided into easy-to-follow sections that include instructions, advice, and helpful hints.

Sci Toys

This web site shows how you can make toys at home using common household materials, often in a few minutes, that display scientific principles.

Try Science

Try Science is a "gateway to experience science and technology through on and offline interactivity with science and technology centers worldwide."  Try the experiments online first then do them at home or at school.