I've been trying to get more visibility into our apps business. iTunes reporting is pretty lean in terms of cutting the data into information that would actually help you run you business and price your apps.
I found this list of applications - some SaaS, some desktop based that read in the information from the iTunes store and turn it into all sort of meaningful charts. Some of these products look promising, especially Heartbeat and AppFigures. I might trial these products.
The killer app for me though, as a multi-platform publisher (not that we sell a lot on Android or BlackBerry yet), would be one that pulls data from all the app stores. Right now, we have 10 apps approved for the iPhone, 4 on Android Market, 3 on iPhone, 1 published in Airtel's operator market, and 3 in Motorola's upcoming Android app store. We have Palm WebOS in development and we are figuring out our Symbian and Windows strategy. I would pay $40 to $50 a month for something like that, especially if I don't have to deal with slow interfaces for daily reporting (BlackBerry and carrier stores).