The New York Times has
a nifty graphic up that lets you see the breakdown of this year's $3.7 trillion federal budget proposal by size of each component. Medicare/Medicaid continues to be the biggest chunk, taking $1.1 trillion (a number that continues to increase each year due to the rising costs of health services, this affects private sector HMOs as well).
Social Security is next at $800 billion. One thing to remember however is that Medicare/Medicaid and Social Security are paid for through separate taxes, apart from the standard federal income tax pool. If you look at your pay stubs you'll see them listed separately, the idea is to keep them self-sufficient and not subject to fights over general income tax funds.
With those two out of the way, the official military budget is next at a number of around $680 billion but that doesn't include
non-DoD defense-related spending which pushes it well over $1 trillion.
The next largest chunk of your tax money is (embarrassingly enough) interest paid to other countries holding our federal debt, the combined accumulation of decades (centuries actually) of not bringing in enough taxes to cover our budget, and borrowing from other countries. We're looking at $474 billion here.
Pretty much everything else is small potatoes compared to those.
