Weather Crafts - soooo awesome, since we'll be talking about the Wonders of Water all year.
Soap Clouds. A bar of Ivory and a microwave = cool science experiment
15 Favorite Science Experiments for Kids
Gum wrapping Tutorial by Woof Nanny, via Flickr - I have fond memories of my older sister teaching me how to do these when I was a kid.
Raised Art with Glue Aluminum Foil and Shoe Polish
Cornstarch and water mixture moves to sound so kids can visually experience sound waves.