While this doesn't have the same hands-on, active participation as most science camp activities, the students loved it! They oohed and aahed and were captivated the entire time.
Summer Science Camp: Chemistry Demonstrations
If you're running your science camp in a full science lab, and you're comfortable with chemistry, consider putting on a chemistry "magic" show for your campers.
Grab your science supply catalogs and look for the chemistry demonstrations (I've gotten them from Flinn Scientific, Ward's Natural Science and Nasco) - they have kits that contain the chemicals (and often anything else you might need, minus the glassware) you need for each demonstration. Look for demonstrations that involve color changes or some other wow-factor. It's fun shopping, but if you're not careful, you could blow your whole camp budget on this one session - choose wisely and realistically.
Make sure you follow all safety precautions - wear your goggles and lab coat and make all the students wear goggles as well.
When you're "performing." show the students the solutions you'll be mixing together and ask them for predictions as to what will happen. Make sure you react appropriately amazed and awed by the reactions, as they occur!
I don't expect the students to learn a whole lot from this session (they're elementary students and there's no way they'd understand the chemistry), instead I use it as an opportunity to build their enthusiasm for science and just have a little fun (it is summer, after all!).