I am writing a Diablo 3 item optimizing utility...
To start with: You can input items, put them in your slots and it will tell you how the properties add up.
It will also take a list of items and automatically produce an optimized loadout of items meeting a set of minimum requirements, or maximizing a particular property.
This is all fairly easy if we are not talking about derived statistics, those formula's are not dependent entirely on items and are subject to nerf batting.
I am running into issues with class progression. I don't know what the attribute progression for each class is. So I wont be able to input level 34 Wizard and know what base strength, vitality, intelligence and dexterity I have in order to determine derived stats like DPS, DR, Dodge Chance. Instead You will have to strip your character naked to find those base abilities. And I can't find the details anywhere. All I know is that they get 2-3 to the primary, 1-2 to vit and 0-1 to the other 2 per level (sum of 5).
Edit: comparing a level 1 wizard to a level 60 wizard, I get 8, 8, 10, 9 and 67, 67, 187, 127. That is strait up 1 to str, dex, 2 to vit and 3 to int. Exactly over 59 levels. The internet has bad data, there are 7 attribute points per level, not 5.