How to keep a child busy for hours in the summer: DIY: Giant Ice Cube Awesomeness - filled with plastic animals, dinos, and such. And I'm sure you could put in food dye before its frozen to color it like the ice block in the photo.
Awesome Light Up Firefly Egg Bug craft to do with the kids! Great for a night-time Easter Egg Hunt or summer fun! Just use an Easter egg, pipe cleaners, duck tape wings, and an LED light or a small glow stick to make it light up like a lightning bug!