Since there might not be an API for diablo 3 AH (at least not at start and maybe never for RMAH), I decided to create my own =).
You use the app ingame (takes screens of AH item listings).
It gets converted to an algorithm before getting sent to server (won't have to store thousand images).
It gets verified by the community (kind of like a captcha).
You get credits for the screen you contributed and pass a certain # of votes.
You use these credits to look up the database.
What this gives you:
A good overview of the AH (if people participate).
Possible graphs by time.
Fast way to price check with reliable sources.
A rough % of what affixes are available for a certain weapon.
These things are not final and for the most part it's already working, if you have ideas feel free to submit them to me.
PS: This won't break the TOS/EULA as it simply is a screenshot program (just like Adria is).
Questions / Ideas welcome =).