The federal government is supposed to deal with international issues and interstate issues. It seems to me that most of the government's time and energy is taken up dealing with things it has no business dealing with.
Education? Disband the department of education. It should be handled and funded at the state and local level.
Transportation? Only deal with the small section of roads which actually cross state boundaries. Not bridges inside of states or tunnels in Boston. Only deal with the point that the roads cross state borders. Air travel. Yes, that is their territory.
Defense? Yes, that is a federal area.
Statues of Vulcan? No. Aside from not being a interstate/international issue, this violates the separation of church and state.
Commerce? Interstate... yes. Shouldn't be loaning money to local small businesses or such.
Taxation? Yes, but I think our current system is crippling us in the international markets and should be changed to a consumption tax instead.
Energy? Interstate transmission... yes. Should stay out of the rest of it.
Laws? Passing laws is okay. When needed and in the domain of the federal government. I don't see what abortion has to do with interstate commerce or international affairs. Likewise for murder or numerous other illegal things(drugs, etc). I'm not saying these things should all be legal, they should be regulated at the state level, not the federal.
Pollution? Water and air pollution.. yes, they cross state borders.
Medicare / Social security / etc? Not a federal issue. If a given state wants to fund and setup a system, great. Some of these programs are good socially acceptable things. They are not in the domain of the federal government.