Breakfast Topic: This is my quest

A little musical interlude for your morning, courtesy of Peter O'Toole and Sophia Loren. On with the topic: quests, of course! With the upcoming expansion, there are going to be a lot of changes happening all through Azeroth, both to the way the world looks, and to the quest givers and quests that we've all grown so familiar with. Some quests will stay, some will change, and some will simply go away, never to be completed again.

There are two quests I recommend that people do now, just in case they vanish into the nether when Cataclysm hits. One is Alliance, and one is Horde, in the interests of equality:

Alliance:
Sully Balloo's Letter: This one is entirely too easy for Alliance players to miss, as there's no indicator on the minimap that a quest even exists. If you go to the bridge over the Thandol Span and jump off into the water below, you'll find the skeletal corpse of a dwarf crushed by a boulder. In his hand is a note with a gear icon if you mouse over it -- clicking it gives you a Waterlogged Envelope that will start the quest. While the chain that starts is interesting enough, it's the letter itself that's noteworthy -- be sure to read it before you turn it in. For history buffs, yes, this is a reference to Sullivan Ballou, the Major from the Civil War.

Horde:
Test of Faith: This quest is pretty straightforward and simple, but players sometimes miss it both because it's in Thousand Needles, and because it's so far off the beaten path in Thousand Needles. You get it from Dorn Plainstrider, who's off in a little cave in the side of the cliffs just northwest of Freewind Post. Dorn gives you this quest, it's really quite simple: He teleports you to the top of one of Thousand Needles peaks. The quest objective? Jump off. I won't say what happens, but it's a long way down.

So here's my question for you Breakfast Topic types: If you were asked to recommend just one quest to someone, one that really stuck out in your mind, what would it be?