Armour dyes would rock, WAR implemented them and it really gives a sense of cohesion when you pick up a new piece of gear and know that it can look exactly the way you want them. It could give the scribes an extension to their profession too.

I do like the way WAR has trophies that you can attach to armour, another level of customisation that could be tied to achievements or epic rare drops. No boost to stats just a trophy for a job well done.

While I'm singing the improbable want song. How about an armour hall type affair in guild housing. Somewhere to hang that first set of tier armour with pride. As a BS I cried a little inside when my Imperial Plate went the way of the vendor. It was a long hard grind to get all that and to trash it was upsetting.

One last one now that we have instanced zones. How about breathing life back into Gnomeragan? Take one epic quest chain, a long hard grind and at the end of it you have a fledgling city that's rebuilding itself. It would breathe some action back into Azeroth and open the game up for extra expansions based on what is now a dead zone.