Above is a chart of the debt ratios in 1996 and 2006 for OECD countries.
Some people are overly focused on the deficit in the United States and believe that the US dollar would collapse and be replaced by the Euro or the Yen. As can be seen in the chart the European countries are not that much better than the USA and Japan is substantially worse.
France, Germany, Italy, Japan have gone into recession ahead of the USA
Country's have debt ratings and the USA has a debt rating of about 20th-30th rank among over one hundred countries
Sovereign credit ratings are discussed at wikipedia
Government debt is discussed at wikipedia
The IMF (International Monetary Fund) has a blog that discusses the finances of countries.
US debt as percent of GDP is looked at over time at istockanalyst