I enjoyed searching for Artifact coffers in XI and simply unlocking tavnazia with all my low leveled friends ^^
Plenty of great moments in XI.
Of course just to say something that isn't FFXI I remember a simple pvp fight in age of conan that started with one person who was higher leveled killing me and a friend and ending with a full guild on guild assault. In the end it was reduced to people unequipping their weapons and headbutting eachother.