I've thought about this for a while now, and I cant see why Blizzard wouldn't try to implement class specific mounts for all classes. Warlocks, Death Knights, and Paladins already have their own special mount, and it wouldn't be too difficult to come up with something for all the other classes. These are just my ideas, so tell me what you think.
Druid : Calls a wild beast from the environment, perhaps one that changes depending on the location and biome.
Hunter : Do I need to say it? Mountable pets. most of them are plenty big enough as it is, just strap a saddle on top.
Shaman : Ghost wolf.
Rogue : A bit more difficult to come up with an awesome rogue mount, maybe a sneaky looking black horse that spawns with a cloud of smoke?
Priest : some sort of holy spirit, or maybe a demon if shadow spec.
Warrior : some sort of war mount, maybe similar to the new pvp horse
Mage : I honestly cant think of anything for mages :/ sorry.
we're in the off-topic section so I'm going to assume you're talking about different classes.
Math: A big number 3. That seems like a good number to ride on. It's kind of like a camel in a way, probably very sturdy.
English: Probably a pencil mount that has some legs or something. Maybe give it wings to stand out, or sunglasses, I don't know.
History: A rich white man, since that's about all we ever learn about.
P.E. : Dodgeball. Just a dodgeball.
By the way though, nerf Math, it's way too strong.