nice! We thought about displaying profit from downloads * price but we found that for most of the big apps, they tweak around prices constantly so the profit would vary too much based on when you poll their prices.
Keep in mind though, like makeshifthoop said, price changes (and even more so, in app-purchases) can have another huge effect on total "profiters" -- some top grossing apps are actually free and rely on in-app
Could I suggest an extra column - Downloads * price