I'd like to throw in ideas about what to do with main professions: how to simplify them, make them more entertaining/profitable, less grindy, etc.
For starters, I'd love it if my scribe could summon a table and chair to actualy write glyphs, and my alchemist summon a mini-lab with bunsen burners and all.
One thing I really liked about Star Wars Galaxies was the crafting. I loved that you could go out and harvest mats and they would vary in quality. Therefore if you were diligent enough about gathering, you could craft items that were better than other people's. I'd like to see something similar in World of Warcraft.
The problem is that SWG had harvesters you could go and plant and set to gather while you were away. You would just have to go and empty them when they got full. There's no way that a setup like that will work in WoW. Too much would have to change.