But in all my time of WoW, and even though I've seen cooler things since (like the AP Eranikus event), there is really the one moment that stands out most for me (and for many other I'm sure), even moreso than the "oh sh!t, what are we gonna do" first peek at Majordomo Executus (which was on the same very late night):
BY FIRE BE PURGED!
(My old warlock on Dragonblight)
One of the best gaming experiences ever right there. :D