The Daily Grind: What quest or questline is the most memorable?

MMO quests are old hat by now, and the vast majority of them are some slight variation on the standard kill-10-rats or FedEx mission. Some are unique, though, in terms of both their rewards and their mechanical presentation.

I'm thinking of EverQuest II's betrayal quests here, which allow you to switch factions, home cities, and in some cases, even classes. What MMO quests or questline do you find the most memorable and why?

Every morning, the Massively bloggers probe the minds of their readers with deep, thought-provoking questions about that most serious of topics: massively online gaming. We crave your opinions, so grab your caffeinated beverage of choice and chime in on today's Daily Grind!