What 'legendary' gigs have you attended? I don't mean in terms of gigs that you thought were really good, but those that have gone onto have a certain mystique/legacy amongst fans - Sex Pistols at the 100 Club, Bob Dylan at Manchester Free Hall when he went electric, that sort of thing.
I went to see Oasis at Knebworth in 1996, but i'm sure lots of DiS people probably went to that. I'm sure i've been to others but i'll have to give it some thought.
Also, for any gig you mention, say whether or not it lived up to the legacy that followed it.