What with the Death Knights possibly getting their own custom flying mount and the Druids having the cool chicken form, I got to thinking, what would a Shaman use if we were to somehow be blessed with our own class-specific flying mount?
Shaman worship the spirits through the four elements and are the conduits through which their power flows. Shaman borrow power from the elements, requesting the elements come to their aid, in such a way shaman have agreement from the elements to hear the shaman's call.
So a good flying mount, lore-wise, would be if a Shaman could call upon the power of the Wind to help them get from place to place. This could actually be in the form of some sort of large wind elemental which the shaman rides upon, perhaps looking like a chimera but made out of clouds.
Our Shaman could have a series of exciting challenges to go through to learn of and tame the power behind such a mount, cumulating in getting the mount itself. In other words, a honking big quest line. I love big quest lines; the lore, the sense of being on a journey, the endless pestering of guildies to come help.
If you want to ignore lore, game-wise something like a frikkin' great big dragon made out lightning and smoke would be awesomely cool, but I'm not even going to attempt to draw one of those. Or even more graphic-card intensive, a smoke monster such as that on Lost which actually shifts forms between dragon, giant snake, etc as you are flying. Not going to happen, I know Blizzard's graphics design department would have a migraine with that one.
As I have hunter and warlock alts, I could also dream up some mounts for them too, but I'll leave that as an exercise to the reader. So come on...