In the FT, Willem Buiter proposes a 5 point plan for a way out of the Greek debt crisis:

• Greece effectively regains sovereignty and can do whatever it pleases, with some exceptions, see below.
• Greek debt held by the ECB is bought by the ESM: The ESM extends long-term, low-interest financing to Greece which Greece uses to repay the ECB debt. “Since most of Greece’s other sovereign liabilities have long maturities and deferred interest payments, payments to creditors would fall sharply.”
• No further financing by the IMF, the ESM or other official sources is extended to Greece.
• The ECB does no longer accept any Greek government debt paper as collateral or for purchase.
• Commercial banks in Greece are recapitalized or restructured using funds from the Hellenic Financial Stability Fund and other sources. The ECB bars Greek banks from accepting any Greek government debt paper.

The plan would require additional European taxpayer money for the ECB-ESM debt swap and the bank recapitalization. It would isolate the Greek banks from the mayhem triggered by government default.

Update: 7 July 2015

A related proposal by Willem Buiter and Ebrahim Rahbari.