This addon will allow you to mount with a random mount. Unlike most other addons of this kind, this one is dynamic. It doesnt check via a set list of mounts, so no need to update it every time Blizzard add a new mount ingame.
It also allow you to "remove" from the randomness drake and mammoth mounts (because they are huge and I know alot people do not like to ride them).
Read the Readme.txt to know how to set it up.