I'm curious about what ideas people have for next expansion, and what kind of things they would like to see added to the game.

For instance, the Legendary cloaks seem to have worked out quite well, with everyone having at least the opportunity to get one, provided that they spend the time and energy to grind it out. My idea would be to add a similar kind of grind to professions for a non-tradeable, massively complex and arduous material list, but non-gamebreaking item.

If this were an option, what kind of things would you want to see for specific professions?

Some ideas:
Engineering - A 400% flying mount, or a personal transport device that can take you anywhere in the world once every so many hours. Maybe a personal moving sidewalk that can be used in major cities, to slowly move you around the whole city, much like in an airport.

Jewelcrafting - A gem, or gems that can be removed and reused. Limit one per character.

Alchemy - A flask that allows you to disguise yourself as the enemy faction, with the added bonus of not aggroing enemy NPC's and players. Imagine an Orc being able to run into Stormwind, able to buy and sell from vendors and the AH.

What else would be fun to see? I have no illusions that any of this would ever make it into the game, but I just wanted to see what kind of ideas people would like to see, for fun and giggles.