A few ways the American federal government wastes money that bother me:
While the US government cuts down on funding for scientific research, education, and consumer protection, it wastes money on things that only benefit special interests — e.g. corn farmers (subsidies) or Christian Evangelicals (faith-based initiatives). Ironically, some of the waste is a result of a lack of, say, good education, especially in the case of manufacturing industries affected by globalization getting federal funding and subsidies. In short, much of this waste is counterproductive and the money could be better spent on universally-helpful things like health and education.
To remain competitive, subsidies and tariffs (i.e. protectionism) are not the answer. They limit consumer choice, waste government funds, and inhibit the benefits of competition, such as better products. In addition, they are created largely to politically please special interest groups. All of the aforementioned wastes of taxpayer dollars do not help the nation as a whole, not do they help a large group of people in need — helping the general public and the needy should be the government's priority, not wasting money on special interests just to get a few more votes (which alienates the general public, I might add).
Encouraged research and development and public education are much better answers to the nation's economic problems than throwing tax dollars down the drain into failing industries — that money could be better spent on things that help the nation as a whole, in addition to those who need the help most. The money spent on failed or worthless causes could do great things, if the government — that includes the White House and Congress — wasn't interested most in pleasing the polarizing special interests and encouraging the negative cycle brought about by all this waste. Heck, if less money was spend on all this junk, taxes could be lowered, thus pleasing the fiscal conservatives. America and its moderate, progressive forces would win, and the backwards and unhelpful groups that much of this money is being given to would lose.
There is debate over whether special interests help or hurt America (see list of pros and cons). They do both. But the ones on K Street that corrupt the US government and contribute to the massive waste of money we see are the ones who need their influence to be lessened, for they hold far too much power and harm the nation's political and financial well-being, hurting progress in economic and social areas, and adding to the apathy felt by the American public. In one sense, special interests are a part of democracy. In another, they harm the principle of the government of the people by taking chunks of influence away from the people, often with lobbying money and perks.
Restrictions on lobbying, on pork-barrel legislation, and on unnecessary and only politically-motivated aid to businesses and industries are needed; transparency in government (spending) must be increased — or the corrupt win. What's more important, special interests or the public interest?