My friends and I have been talking about this for awhile, so I figured I'd post it up on here. The rules are, the mount can already exist or be something entirely new, but it has to make sense, lol.
Forsaken - Bat
Orc - Wyvern
Blood Elf - Dragonhawk
Tauren - Roc
Troll - Windserpent
Goblin - Hot-Air Ballon
Human - Pegasus....I guess, lol.
Gnome - Mechanochopper
Draenei - Moth
Dwarf - Gryphons
Night Elf - Hippogryph
Worgen - No Idea!!