For some reason, crafting has always been a big part of massively multiplayer games. Maybe it's their quality as loot-collecting simulators, but from the very early graphical MMOs, players have almost always been able to create and modify and trade and sell items of their own. Though we don't talk about it as a mechanic much (you press a button and get what you crafted, what's the big deal), it's certainly one of the main reasons people play World of Warcraft, and the crafting system has come to not only fuel the economy, but has ended up becoming one of the best ways to show off and present your customized character.
So our question today is: what's your favorite or most important crafting item? I'm in the middle of leveling my paladin, and he's just now reaching the highest reaches of Engineering, which is a skill I've never leveled up before, but have always wanted to. I haven't gotten together the gold for epic flying yet (well on my way at level 73), but I did make normal flying machine as soon as I could. And my big goal with this character, other than getting him raiding ASAP, is to make the Mekgineer's Chopper -- ever since we first saw it in the early days of Wrath, I've planned to get a character up high enough to make it. I know, I know, I can buy it, but for me it's a crafting thing -- I want to go out, find what I need to find, and craft it with my own virtual hands.
Any other crafted items that have you wanting to make something for yourself?