I have advocated this before and here I go again. However there are a set amount of tamable creatures, there still are different skins all over. Now, unfortunately that does not mean that there are enough skins to be original in the looks of your pet.
There ARE some pets though that are only obtained at low levels and that have unique skins in the entire game. The low level means that there are not many high level players that bother to go back and level those pets all the way, making it so that you need to tame them in your early levels...
Now I myself have two of these pets (which I think are the coolest looking besides the least common ones), which are only examples. Bear in mind: I am alliance on this hunter (yes I have a few) and for alliance they are a bit more exceptional than for hordes, simply because they are situated in "horde" areas.
- white-skinned bat, Ressan the Needler, level 11, rare (but nearly always there), just northwest of Undercity: http://petopia.brashendeavors.net/html/skins/skin_batskinwhite01.php
- rotting-skinned black boar, Rotting Agam'ar, level 26, elite, inside instance Razorfen Kraul: http://petopia.brashendeavors.net/html/skins/skin_boarskinbluearmored.php
To seek yourself for unique skins, or pets that you don't see everyday, just use http://petopia.brashendeavors.net/ like suggested above.