The pet pack exists as Purreau's Plentiful Pet Provisions, and the Hoard of the Hydra pack contains some faerie-themed gear. But another Avalon pack wouldn't hurt, with more elven items.
A fellow Wizard mentioned the idea of Super Hero themed packs. That idea although will have a few challenges before being implemented, would be cool.
An Animal themed pack would also be cool, maybe offer clothing with animal themes like Leopard Spots or Tiger Stripes which are all dye-able of course.
And within this pack, there'd be a chance at most of the animal themed mounts we've now, possibly a few new ones and the Charity White Tiger!