> a crypto which is relatively stable could be very useful ...

It seems like there's a fairly tight correlation between the value of a cryptocurrency and the effort required to mine it. (Which is what you'd expect -- if the price of BTC rises, more people mine it, and the per-block difficulty increases, and if the price falls, fewer people mine it, and the difficulty falls.)

I wonder if we could create a more stable cryptocurrency by keeping the mining difficulty constant (or possibly tied to moore's law). It may be wildly "inflationary" in terms of the size of the monetary base, but it should be fairly stable in terms of real resources per unit of currency.