There's only so much you can do with an empty pizza box besides throw it away, or let it clutter up the floor of your filthy hovel. There is on other option though: you can turn it into a remote controlled plane.
Granted, unless you just happen to have a remote control setup just lying around, this isn't going to be particularly feasible. But Instructables user Darren Lewis laid out all the steps for you just in case. Guts, controls, and motors aside, restructuring a greasy cardboard box into something that can actually sustain flight is pretty cool. And maybe you could even make a glider out of that.
The only real bummer here is that the boxes are empty. If somebody can develop pizza boxes that fly with the pizza inside, we might be on the verge of a true utopia. [Instructables]