One of the first photo projects I can remember my dad and I working on was stopping the splash of milk dropping into a dish. Nothing spectacular, but we did wind up with some pretty cool shots. Shattering light bulbs and popping balloons work pretty well too. And if you try the balloons, be sure to put a little baby powder in them.
The trick is to shoot in the dark and let your flash take care of the exposure. A flash burst is much shorter than anything a shutter can do on a standard camera.
Rather than dig through years of slide film I’ll just link to another site that explains a technique pretty close to what we did.
Freezing fast motion (AKA High Speed Photography), can give some pretty special photographic effects. High Speed Photography is used in physics, health research, sports and more. This guide describes how to capture super fast movements using ordinary camera gear and a little home made electronics. I will describes the setup I used the problems I encountered and what I did to solve or work around them.