See this new excellent interview with George Selgin. I think it is harder to find any bigger expert on Free Banking theory and Free Banking history than George. Great stuff – even though I do not agree with everything (yes, believe it of not – I do not agree with everything George is saying).
George in the interview recommends that the Fed should introduce a NGDP target rule as a second best to his preferred solution to abolish the Fed. George thinks that a NGDP target rule could be introduced as a Bitcoin style computer algorithm – similar to what he suggests in his recent paper on Quasi-Commodity money (in the paper he discuss a Free Baning solution rather than a central bank solution). I personally think that a Quasi-Commodity standard could be the future for Free Banking money, but I think Scott Sumner’s suggestion for a futures based NGDP targeting regime would work better as long as you maintain central banks.