I love this idea, i once wrote to KI to ask them to put a heckhound mount on. i guess if they can have horses, dragons and cats they could do this too.
I would really like to ride on a centaur or on the shoulders of a type of furry yeti/Sasquatch-type beast. Possibly also a unicorn, but I'd also be interested in seeing some more wing varieties (although I don't buy crowns).