WarcraftMounts received a nifty update that may interest some pet collectors - mount pages now show corresponding companion pets (if available)! My favorite so far is the Enchanted Fey Dragon paired with the Sprite Darter Hatchling. :3
Currently there's no option to filter just mounts that have pet counterparts, so for quicker browsing you need to have some knowledge of pets that look like mounts beforehand or an idea of which mount/pet you'd like to match with. It also seems that not all possible combinations have been implemented yet, but the more obvious ones appear to be up for now. I can already spot a few mounts that need to have a little buddy included on their profile page. :P
One thing that may be tough to get past is determining which pets go with which mounts. Do they have to match in every aspect? It's debatable and pretty subjective.
Some pets are blatant downsized versions (examples: Blue and Red Dragonhawk), but others require more of an open mind to match it up with a mount. For instance, the Little Black Ram could go with any of the Alliance level 20 Dwarven mounts, but it will only match the mount's model and not the color. Players don't have access to a level 20 black ram mount, so the Little Black Ram will never match 100%. It will ultimately be up to the administrators of WarcraftMounts to decide which factors to take into consideration when adding corresponding pets to mount pages. With such a tough decision to make for each mount and pet, I don't envy them and their task. :P
Hopefully more will be added soon, as it could be a useful resource for collectors since pet collecting and mount collecting can go hand in hand.