"A billion here, a billion there – pretty soon it adds up to real money."
Senator Everett Dirksen
The Frustrated CFO's note:
According to Wikipedia's article on the US Public Debt, as of January 9th, 2012 the gross debt was $15.23 trillion, of which $10.48 trillion was held by the public (i.e. in government issued securities, such as T-bills owned by investors like you) and $4.75 trillion was in intragovernmental holdings, such as, for example, the Social Security Trust Fund (i.e. backed by your money anyway).
I urge you to watch the 1965 video below and pay attention to the numbers that were the subject of Senator Dirksen's concern back then.
The Frustrated CFO 