I think it would be nice if players could search the auction house using some filter.
While I can search for "swords" "bombs" or any other type of equipment, and use the text search, it's still a bit coarse.
e.g. If I want to search for a sword (any sword, or a specific one via text search) only in a CERTAIN PRICE RANGE.
Or if I want to look at all swords (or, say, recipes) that have a CERTAIN STAR RATING.
I think these two basic filters could help a lot with searching for items and recipes in the AH.
You can sort the search results by price and stars (even variants if you want) with the little pull-down menu in the upper right, in addition to the text you're searching for. Just start looking when your category has come up and stop when it's passed.