Does anyone have any ideas for an experiment on collision (elastic/inelastic) or impulse (mechanical) or energy transfer?

Please help me brainstorm! It's a wide topic, so anything goes, as long as it yields something interesting or fun.

Lab equipment is not a porblem. I have access to a MacReflex (high speed camera/motion sensor thing), an air hockey table, among other measuring devices and gadgets, and I can get pretty much anything needed.

I promise I will inform you of the outcome of the experiment!