We prefer to keep WarcraftPets dedicated exclusively to companion collecting and pet battles so we can continue to bring you the most thorough coverage. To track your mount collection, we recommend Mania's Warcraft Mounts
fansite. FYI - they're currently doing some nice updates with the site (no ETA on completion), so it will become even more expansive.
Beyond that, you're welcome to discuss mounts and mount collecting in our World of Warcraft forum