I love the solution Austan Goolsbee semi-seriously proposed a few years ago: "re-base" the penny.  That is, declare that all Lincoln pennies currently in circulation are now worth 5¢ alongside the nickels (and then remove the nickels from circulation as a natural phaseout).  Subsequent mintings of the penny would actually say "FIVE CENTS" but the old pennies would also be worth 5¢.<p>Advantages: The five cent penny would cost less than five cents to mint.  The expensive nickel would no longer be minted.  Immediate but relatively contained inflation that puts the "printed" money in the hands of the poorest people (who would have more pennies as a percentage of their cash on hand than richer folks)---a lightweight form of stimulus.  Brings pennies back into circulation because they're not worthless anymore.<p>Disadvantage: vending machines wouldn't accept pennies for the new amount, but most don't accept them at all so that's less of a problem than it might be.