According to the World Gold Council there were a cumulative 169,100 tonnes of gold mined by the end of 2010, all of it still in existence since gold practically does not degrade, react, corrode, etc. At the recent high price of $1,800/troy oz. its total market value was $9.8 trillion, or 16% of global GDP.
Using data from the Federal Reserve (US debt) and the US Geological Survey (annual global gold production) I come up with the following chart.
The value of gold is essentially a psychological phenomenon, since it has very few tangible uses. At 15% of global GDP, up from 5% just six years ago, it seems to me like it is discounting a lot of panic (the euro will fall apart, the West will inflate away all of its debt, the US will devolve into a second-rate power, etc. etc.).