Wasteful Military Expenditures
The lead editorial in the New York Times for April, 2008 explains how Congress approves spending vast sums to buy weapon systems from military contractors; the final bill is usually far higher than was agreed on, and quite often the weapons don't work as promised. But the contractors to not hesitate to pocket their enormous profits and pay generous "campaign contributions" to the obliging congressmen who put over the deal. Everybody has reason to be pleased except the U. S. taxpayers who provided the hundreds of billion dollars.
Finally, the principal argument to justify all this is "Do you know how many jobs would be lost if this contract is cancelled?" And if a member of Congress should object the response is "Do you know how many jobs would be lost in your district? We will tell all those voters that you voted to put them out of a job." Therefore, the appropriations are almost never denied.