There seems to be a growing awareness on both sides of the political range that to let the United States' fiscal health go the way of Greece would not be a great thing, and that we're not going to cut our way to a balanced budget because Americans love their Medicare and other entitlements way too much. So that means tax increases. (No, nobody is talking about doing this while the economy is still in the dumps.) The most-talked about tax is a European-style value added tax, which would basically be a federal sales tax levied all along the production chain. Among its attractions, a VAT is easy to administer and difficult to cheat against.
Here's former Fed chairman Paul Volcker, a Democrat, according to Reuters:
And here's Greg Mankiw, who was chairman of President Bush II's Council of Economic Advisors, writing in the NYT: