The shows i've been to haven't been particularly violent.
Oddly enough though, the most violent show for me was also the less crowded and calmest in general.
It was the Seelenschmerz festival last October in Athens. I was in the front row for more than 6 hours, patiently waiting for VNV Nation to come on stage (and meanwhile enjoying Diorama and Adrian Hates, and laughing at various other bands). Shortly after the much expected last set started, a ~2m tall guy came right behind me and started smashing me repeatedly against the fence. I was already quite excited from the show, so it didn't take much for me to lose my temper. I decided to pass my message to him through my elbow, thus plunging it in his stomach and pushing him back, at approximately the upteenth time he dropped himself on me. From what i learned afterwards, he gave an angry look to my companion, who was smart enough to give back an apologetic look and avoid the fight, but foolish enough to try to relocate me without explaining the situation to me. After a small quarell i accepted the relocation, got saved from the tall idiot, and watched the show from a worse spot, while receiving another idiot's elbow on the top of my head for the rest of the evening. :Spin: