I had an interesting conversation with Miles Kimball at his blog concerning his idea of splitting the Euro into a North Euro zone and a South Euro zone. This seems like a far more realistic solution than reintroducing drachmas, punts, pesos, and lira. Nevertheless, there are some thorny issues here which Miles says he will address in future blog posts.
In short, a South Euro will quickly depreciate. Because wages are sticky, exports from the southern Euro zone will be relatively cheaper than exports elsewhere, providing a short to medium term boost to Greece, Italy, Spain, and Portugal.
One concern here is that the continued circulation of North Euros in South Euroland, as well as the North Euro's continued use as a unit of account in South Euroland, would make those living in South Euroland highly cognizant of nominal changes and therefore less likely to fall prey to the degree of money illusion that is necessary to drive an export-led recovery.
Of course, as Miles points out, his is a fourth best solution, so one should only nitpick so much, never mind the fact that it takes a solution to beat a solution, and I don't have one.