Let's face it, navigating and trying to find stuff on the AH is a mess. I spend almost as much time questing as I do browsing page after page just to find stuff I want to buy. How about adding a search bar to filter and show only items I'm looking for. Only looking for a flaming burst great sword or great axe? Bam, type one word and I can see what's available. It would also make it easier for people posting to see what the current market is on the item they want to sell. I know some people would argue that it would make it easier for people to farm the AH and take all the good buys or would cause lots of undercutting. It sucks though to have to page through all those auctions, buy something and find out a few pages later you could've saved some PP, or go back to the cheapest one you saw only to find someone bought it already. How about a checkbox to filter items I can't use rather than look at all the items with X's because they have a racial requirement or guild level.
Nothing is worse than a bank littered full of half used wands you got from turning in all those collectibles. Just about everything else is stackable so why can't I combine wands with less than 50 charges?
What's up with 1 item attachment per mail or the crazy cost associated with sending some items? It's tedious enough to transfer items buy moving things around my banks, logging and relogging on multiple characters, but on top of it mailing stuff isn't an option either.