It's really hard to capitalize on this, because noone really know what's going to happen. The only thing you can bet will happen is an increase in volatility in financial markets, but I'm sure that the counterparty would take that into account and appropriately increase the price of volatility bets. The only thing you can really do is take a one-sided bet (e.g. short/buy Greek bonds), you win if you're right, lose if you're wrong.