I was thinking about these calculations.
Given BTC's price you can predict the hash rate such that you know if it is a good time to purchase more hardware or not almost in real time.
That would make an awesome online calculator/ alert.
Especially if we get to next day shipping from our asic suppliers.
This one is less about prediction and more about looking for current anomalies in average weekly hashrate. I'll post the long term prediction results soonish. That might be helpful to know going forward.
EDIT I'll do the long term predictions next week and provide the necessary calculations that someone can use to create a calculator.