In a post-Apocalypse world, what would be the new money?

Our paper currency is a faux-currency. It has value because we say it has value—because we all agree it has value. In a world where there was no national gross-domestic product to back the value of a US dollar, or a Japanese Yen, or a British Pound, faux currencies would only be worth the value of the paper they are printed on. Many turn to gold as a currency of last resort. But gold has little intrinsic value either. If you were marooned on a desert island, gold would make a lousy pillow, or bed. You couldn’t eat it. Nor could you take it as medicine to treat an infection. More mundane articles like pillows, bedding, food and medicine would be of far greater intrinsic value than precious metals or jewels.

So as we prepare to welcome 2012, or have already done if you live in certain time zones; can we think fancifully about what we’d do if the 2012 prophesies came true and we survived but civilization as we know it did not? What do you think would be used initially as currency for trade?