Put a glow stick into an empty water bottle and it works like a lamp, giving you extra light.
If you still have your old soft play mats from when you were little, they make great soft flooring for the inside of your tent. That grass can be hard!
The tops of acorns make great whistles if you want to signal to your friends in the woods.
Don't have a fancy camping bed? Well, flat pool floats do the same job! And they look a lot more fun.
Some string, charms, and citronella or tea tree oil is all you need to make a bracelet that can keep mosquitos and other bugs away.