A new section has been added to the website, Tools, here you can find three calculators to help you with your auction house needs.
Real-Money Auction House Profit Calculator
Calculate profits for both Battle.net Balance and PayPal (or other authorized service) cash outs after Blizzard's transaction/transfer fees on any item or commodity.
Gold or Real-Money Auction House Calculator
Should I sell this item in the gold auction house or the real-money auction house? This tool calculates how much gold is earned from a successful auction in the gold auction house as well as profits for selling that gold in the real-money auction house after Blizzard's transaction/transfer fees.
This tool calculates profits earned after reselling an item. Find a item for cheap and wanna know how much you need to sell it for to make a profit? Use this tool.
More tools will be added in the future! If you have any feedback on the current tools please post in the forums or send me a message. Do the same if you have any suggestions for new tools you would like to see also.