What I'd like to see for sale on the Blizzard In-Game store.

Recently WoWJuJu pointed out a new Elixir coming out on the PTR that grants 100% xp bonus. Current WoWhead notes have it usable at level 85, so as soon after your upgraded heirlooms and/or guild heirloom gear has stopped working for you. Makes for that run from Cataclysm to MoP quicker. (I know a few guildies that would love that). The main problem most people are having, it looks to be sold from a real-money vendor => "5.4 - In Game Store - 100% XP Buff (Tracker)"

We are currently exploring the possibility of adding a way for players in certain regions to make purchases directly within the game. As part of this process, elements related to this will be appearing on the PTR. We’ll provide additional updates on our plans as development progresses. (source)

First off, I speculate 'certain regions' stands for US (and neighbors) because close to home and no major currency exchange required (RL: I work in an IT field, we like to 'test' out new features on ourselves first.). They can stock the local retailers (ie Gamestop, Best Buy...) with new "Blizzard Bucks" that grant me in-game credit (not gold, right?!?) (BTW, a model that Microsoft/XBOX is going away from). Now my nephew who doesn't have a credit card can go and purchase something from the Blizzard in-game store. He can use the character wardrobe function to see what the pet, mount or vanity item would look like with his main, before plopping down his money. 

What would I like to see on an in-game store? 

Sample BL2 Siren Mods

1. Items currently available on the Blizzard website. (They already brought the knowledge base online). Now let Elk grab that new rabid bat mount directly from a vendor in-game. Can you make him a talking crab?
2. Appearance change. Gearbox just started this with various new 'skins' for the Borderlands 2 players. The skins do not add to the game play, but simply make your character have a different head or body. For about $1, I can purchase specific new 'head' to my character and use it on any of my players of that type. Blizzard could offer up pre-done 'popular' options. "Surfer Blood-Elf" includes random face, blonde hair, tan skin and piercing in both ears. Or maybe by purchasing the appearance change, it unlocks the character creator screen at your next log on. 
3. Heirloom items - This could be a way for Blizzard to allow account-wide transfer of (BOA) items. Once your account has some achievement, you can 'buy' an XP buff from the in-game vendor that would replicate your heirloom gear. The price would be like buying from the guild vendor, some nominal amount, but something Blizzard can track (1 cent real world?). 
4. One-off skills - How about the ability for my herbalist/alchemist warlock to ride my tailor priest's magic carpet? It was a tiny bit irritating when my 'random mount' add-on would fail because it randomly picked the magic carpet. Wait, is a magic carpet a status item?? Ok, how about you buy my herbalism LifeBlood skill in return? 
5. Vanity items - sure the Top Hat market is absolutely crazy, and Blizzard selling one on via an in-game store would kill it but I want one for my bank alt! Maybe it could be like the iTunes App store and you could submit art to Blizzard for approval. For every piece sold, I could get a micro-royalty. I could whip out my art supplies, draw up a steam-punk themed vanity item that could be applied to the my existing gear. Or how about a sort of a reverse Cos-play!? My virtual character looks like me in RL?! 

Enough pure speculation. I guess we'll need to wait to see what happens in the next few months..