If you feel the need to ask on an Internet discussion board where you should invest to profit from $X, that's probably a good sign that you should just keep your money where it is. Flippancy aside, the most likely result is going to be downward pressure on stocks generally and European stocks in particular.

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.

Some think the modest rise in bitcoin prices is a consequence of the Greek difficulties. For example:

http://www.reuters.com/article/2015/06/16/us-eurozone-greece...