Feature request: calculate a weighted average of and/or history of trading prices for each fiat currency.
I know that most people price their trades based on some formula using bid/ask/last prices from the major exchanges. However, given the divergence in prices between Mt. Gox and other exchanges, it would be very useful to have a bid/ask/last/depth based on what local bitcoin traders have actually decided to set their prices to.
It can be exploited by creating several accounts and selling to self at an unreasonable price. The average will then go off. If exploiter is a buyer, he will make price go down. If he's a seller, he will make the price go up.