Probably Slayer in April 1999 at the Warehouse in Toronto. Smaller venue (3000 capacity) than Slayer plays these days. My friend Will went into the pit and came out five minutes later with blood dripping from his mouth, a ripped T-shirt and three broken ribs. I saw a lot of people get hurt that night. Probably due to the crowd being a lot of casul metal fans who didn't know a lot about "pit-ediquite", just going out with the intent to kill thinking that's what you're supposed to do.
I stayed away from the pit.
01/18 & 01/19 -- Godspeed You! Black Emperor and Neurosis (in Montreal)
02/08 -- Dark Tranquility
04/11 -- Black Sabbath
04/24 -- Nile