Foreign aid should be reduced and eliminated in some cases. Research in not essential areas should be reduced. Government entities can be reduced and/or eliminate. In fact, I will specifically call out the group who decides what goes on postal stamps to start.
Overall, I believe every aspect of government overspends and wastes. Therefore I would argue that all government needs to find a place to reduce, permanently, 5% of spending. This can be completed through implementing Lean Techniques and review of procedures at the lower levels, not managed from up high.
Government has a tendancy to manage from high up and let things filter down without knowing how things changes from the 50,000 foot view, to the micro and macro levels.
There is plenty of excessive spending this country can cut without impacting anything remotely signifcant. It comes down to changing the mentality that the government does not have unlimited funding and priorities are not all the same. Some things are more important than others; people will need to be upset that their mutli-million dollar art sculpture may not be as important and developing antibiotics to save lives.