I highly divisible universal currency being tested by banks. Might not be a horrible idea. Remove the necessity for currency exchange markets. If you economy is tanking, the price of goods increase but based off of a universally monitored and controlled currency with a specific market value. I don't necessarily like the idea of the value of the currency fluctuating independently of a given nations inflation, but the idea still would have merit to investigate.
I personally think it is a horrible idea. On the plus side I don't know of any banks that are interested in doing something like that.
If you are confused, the banks are only testing the "ledger" ability of block chains, not the "currency" aspect. The idea is that a block chain would be associated with asset (stocks, bonds, gold, whatever) and this asset could be traded directly between institutions and people without a trusted intermediary (a.k.a. the middle man). One interesting application, which boarder on science fiction, is the self-owning driverless car.