The Economist has a fascinating little piece (by subscription) on the world's leading currency, which is threatened by hyperinflation.
But don't go on a bank run just yet, you Americans out there (it'll be the ? soon anyway if the $ decline continues)! The Economist is talking about airmiles outstanding world wide. Apparently, unredeemed airmiles amount to over $ 700'000'000'000, and that's more than the $ M0 (a subset of M1)!
It seems that miles are sold by carriers (mainly to credit card operators) for a little under $.02 and to the consumer, they are worth between $.01 and $.1 a mile. So, "printing" this currency is a highly attractive source of cash to cash strapped carriers, which is why the amount of outstanding miles has been growing by 20% p.a. over the last decade. Every monetarist on the planet will tell you that in that kind of environment hyperinflation is inevitable, especially since the $ value of a real airmile has been dropping drastically over the past decade with the arrival of discount carriers.
Apparently I have had a very acute sense of that hyperinflationary threat without even knowing, because I never let my airmiles account balance with Swiss get out of hand. Just like the folks in the 1930s who were running to the bakery to buy a loaf of bread with their bags full of millions "worth" of their cash salary payment ...