I've been on the grind to the 5000g for my epic flying mount lately, and I've been playing the Auction House like a demon: calculating, buying, selling, and crafting my way to as much gold as I can throw together. And while Auctioneer has definitely helped, the best way I've found to track prices and make sure I get the most for my time in the AH is just to see the prices themselves -- no average price calculated by Auctioneer is worth enough as seeing the real thing. And that's where Blizzard comes in -- while there are a few sites that attempt to track prices with various methods, they have actual, constant access to the prices on every server. And they have a great place to put them: on the Armory.
The item pages on the Armory right now are practically empty -- besides some vendor and reagent information, there's almost nothing there (especially compared to, say, Wowhead). Giving player access to AH information would pull them into the game even when they couldn't play, not to mention let some of Blizzard's most talented web programmers -- their fans -- at data that they could do tons of great stuff with. Want a text alert when your favorite mats drop in price, or when there's room on the AH to finally sell off those Elixirs of Agility you've got? By passing out AH info to the Armory, Blizzard could give fans access to the data needed to make their own great tools, not only leaving Blizzard free to work on actual development, but giving us Auction House haunters all the access we need to track prices and have that much more fun playing the AH.