Single world currency?

This concept isn't quite new. In fact, it's been floated since the 16th century, and came close to being instituted after World War II. A universal currency would be much more efficient and mean an end to chronic currency crises around the world; it wouldn't be subject to exchange rate fluctuations because there would be no competing currencies to exchange against.

The scary news is that it would require the creation of a central body formed to oversee the monetary policy for a single world currency. Think of another U.N. or a branch thereof with all the dysfunction knows to that kind of agency. In fact, a private initiative would be highly preferable; an alternative like Bitcoin that would take the world by storm and make everyone leave the state controlled monetary systems in drove.

Something based not on the value of gold but on a vital human need we use today and will use forever, let's say a unit of energy, like the Watt. I like this later incarnation...