I know that there are several different groups trying to establish non governmental currencies right now. I haven't followed it all that closely, but people who do seem to think that digital gold has the most promise. Game currencies like those used on Facebook, Online or what ever that sims type game is called are essentially currencies that are somewhat convertible.

There is an effort mostly led by the Chinese to establish a new global currency that is really less than a wet dream at the moment. They hope to use Special Drawing Rights with the International Monetary Fund.

It will be interesting to see what the long run future of nongovernmental currency is. The nice thing about governmental currencies is that there is an incentive for governments to maintain the value of their currency so that they can maintain their credit ratings, it has never been made clear to me what enforces the discipline of nongovernmental issues of currency.

A funny thing about this digital currency is that the creators seem to think that it should guard against inflation because there is no central bank involved. It's true that central banks can create inflation, but not that inflation is only a phenomenon caused by central banks. Central banks tend to make inflation and deflation more predictable, predictability is usually considered a positive quality in a currency. This currency could change value rapidly if it became more popular, and would probably fluctuate a lot in sync with the financial cycles.