My physics teacher just got a camera that shoots 1000 fps. It's not HD but it was still pretty awesome. He used it for a demonstration where he hit a tuning pitch, then we went outside and threw waterballoons at shit, kicked balls, threw stuff at people, and watched it all in slomo. I'd say the coolest thing was popping a waterballoon with a needle.
The guy spitting fire, the green blob, and the jello were pretty nuts though