We shouldn't nationalize the Fed until they QE their way into more and more treasuries ownership. The Fed is the single largest holder of publicly traded US federal debt.
Currently there is about $10 trillion of publicly traded debt (surprisingly, the government owes itself the most, via loans from social security). Back in March, the Fed owned about $2.5 trillion of US debt. That number keeps growing.
If that amount grows, not only is the Fed worth replacing with a transparent arm of the Treasury Department, but nationalizing it would eliminate 20% of the US debt. And bring control of issuing currency back to a more rational process.