First, the server I run the code on can go offline at times. Now, I made a PHP script that uses the new API feature to get the whole auction house and locally manage the data and store in a database.
Demo site:
http://ahawk.ziuo.net/
The idea first was to make a tool that anyone can use to be notified about when a certain item appears, even if the item price is below a certain threshold.
Now what I got since that idea is not quite yet like what I first planned. :P
In any case, I can image some team taking this seriously and making a service that allows better price analysis of the market and not to mention you can now do it outside of the game so it should be even more efficient!
You only need to code the programs efficiently, the armory is a huge plain text json file so you'd need to store it and manage all the data as fast as possible if you got a huge website that serves thousands of users per day.
Anyone else made some neat tools regarding the AH and the new API feature? Maybe someone already did make an AH site that I haven't yet heard of, if you have do share.