The Economist has a fascinating webpage that allows readers to look at all the world's nations and compare them based on various measures of government debt (and for various years).
The most economically relevant measure is public debt as a share of GDP, and you can see that the United States is not in great shape, though many nations have more accumulated red ink (especially Japan, where debt is much higher than it is even in Greece). As faithful readers of this blog already understand, the real issue is the size of government, but this site is a good indicator of nations that finance their spending in a risky fashion.
By the way, keep in mind that these figures do not include unfunded liabilities. For those who worry about debt, those are the truly shocking numbers (at least for the United States and other nations with government-run pension and health schemes).