Getting back to throwing things, some friends and I were at the last (I think) Texxas Jam at Rice Stadium, and toward the end of the night some of the crowd got in a food, beer, anything-you-can-throw fight. It was between the crowd on the field left of the stage and a bunch of people in the bleachers close to the field - all the concessions were in plastic or paper, so it was mostly harmless mayhem. It was in the summer, July or August I think, so maybe the heat got to them.
Speaking of on-stage violence, I'm surprised this one hasn't been mentioned this:
Phil Anselmo and Dimebag Darrell were the dynamic duo. What happened after Pantera?