The Ketchup Experiment! Kid friendly site with lots of neat experiments! It has one that makes a rocket out of a film canister, which would be good for an grade space unit, but it has to many kid friendly expiriments. Great site for any science teacher.
Another science fair idea: Make rainbow roses by splitting the stems into strands and placing each one in food coloring. The roses draw the food coloring into the petals.Hmmm not a bad idea for Amarah's Science Fair Project!