City of Heroes offers wings, kilts and trench coats among other items (see video in link above.) Everquest II just granted its long time subscribers an item that reduces the maintenance costs of player housing and also offers potions that increase experience gain for short periods of time.
I think we can all agree that WoW should offer something similar to long time players. The question is, what should it be? A special mount? A new tabard? Sparkly particle effects? Let us know what you think.