Woodstock 94 was pretty crazy, returned for the 99 diaster. (I left before the rioting took place.)
Seen Primus many many times, but this particular show the second set they did Pink Floyd's Animals album in entirity. That was pretty intense.
Beastie Boys in Brooklyn at McCaren Park Pool. (Only show they played in Brooklyn ever, also was outdoors)
Brooklyn Hip Hop Festival some years ago. (Chubb Rock, Black Sheep, Buckshot, Fat Joe, and Ghostface Killah. Its a must to see Ghostface live, best live Wu show IMO, even better than Method Man I know I'm forgetting more names that played this event. Also was outdoors)
MF Doom in Times Square.
I can go on and on about the tons of shows. I'll just run a list of who I've seen live.
Slayer, Metalica, Rage Against The Machine, Primus, Cypress Hill, Anthrax, Queensryche, Wu Tang, Beastie Boys, Bush, Stone Temple Piolets, Aerosmith, Guns And Roses (1995), Skid Row, Red Hot Chili Peppers, Live, Iron Maiden, Velvet Revolver, Ozzy, Black Sabbath, Pantera, Manson, Limp Bizkit, Pharcyde, Raekwon, Tool, NIN, Rollins band, No Redeeming Social Value, Body Count,.....and thats not even all of it ...i know I'm leaving out like another 50 acts.