This idea has been making the rounds on monetary theory blogs recently. Basically, the Treasury has the power to create money in only one form- platinum coins (those collectable things that you sometimes see advertisments for). There seems to be a loophole however in that Congress never actually set a limit on the denomination of said coins. That means the Treasury could create a trillion dollar (or whatever) coin and deposit it at the Fed. In effect, it could use this little loophole to conduct monetary policy, something which it is not meant to do of course. Or it could do it to pay off the US debt or a number of other scenarios. Quite crazy.