Just a quick note, inspired by reading this and this from the Economist. Here is the unemployment rate in Greece from 1976-2011 (the blue line is an annual series and the red line is a more recent series calculated in slightly different ways, hence the slight divergence):
More recent updates suggest that the unemployment rate in Greece is higher than it was in the US in the depths of the Great Depression. The world was largely on a gold standard system of fixed exchange rates (much like Greece, Germany, and the rest of the Euro-zone are on a fixed currency), and as countries left the gold standard, they tended to experience an immediate and large increase in production and employment. While the pain of leaving the Euro would surely be great, currently 1/4 of Greeks who would like to have a job, do not have one and cannot find one. That pain is real, immediate, severe, ongoing, and palliable. This outcome is a terrible outcome, one of the worst outcomes* and–in the absence of my preferred currency arrangement–leaving the Euro is the only answer for Greece.
*One of the worst outcomes short of global war, the last of which broke out in response to, amongst other things, 23% unemployment.