Top of my head contributions:
King's X in the SFX 1990
Practically empty, I went sort of knowing one album. Blew me away, fan for life etc
AC/DC & King's X in the Point 1991
My first love and my new love together. It was almost too much. I was into AC/DC for 10 years at that stage yet this was my first time to see them. Because King's X were supporting we were there stupid early but that also meant we were in the pit with loads of room while people not 10ft behind us were being crushed. Unbelievably exciting gig which started the day before when I spotted Doug and Jerry from King's X in Burger King on O'Connell st. I went in and chatted to them then walked to O'Connell bridge chatting all the way. A few weeks later Doug sent me a 12" single with a hand written note "Thanks for being there". I later found out that they were having an awful time on the European tour. Still have it.
Marillion in the SFX 1985
I was 14, I loved Marillion still do. Enough said.
Metallica, Point Depot 1991
Black album tour, first tour in the round. Not their greatest musical moment but the atmosphere and excitement in the venue was something else. I don't think I've experienced anything like it since.
Teenage Fanclub, Feile in the Point 1996?
Teenage Fanclub were stuck on last after Foo Fighters, Manic Street Preachers etc. Most of the crowd left after the Foos so you could easily stroll up the the barrier and just watch them. They didn't seem to care and were just perfect.
I'm sure there's more...