I think PVE-wise, the most memorable raid was one of our Agnarr the Stormlord kills in BoT. I don't even remember exactly what went wrong, but basically, we entered his room, got all slaughtered, and one ranger started kiting him round and round and round. Meanwhile, we rezed everyone where we could, sat for med, rebuffed, and then started to cheer the kiter. Who was on chat "hey, is the MT ready? No, really, can you get him off me???". And we kept on cheering.
(after a while, we got the big bad back in the stairs and killed him. Said ranger made a warrior named Agnarr in WoW in memory of that one, and was MT for most of vanilla)