While you're thinking about it, what would *you* ask America to do, to sacrifice, if you had the the kind of national attention these candidates can get, both as candidates and potentially as President? Write to them about that too.
In addition to the question of giving blood, one big thing I saw missing from both of their discussions of an energy plan was manpower. George Bush has made some somewhat lame mentions of the fact that some Americans are dealing with the gas price problems by driving less and riding bikes and such. Sure we are! And we should do more! Don't we have a national struggle with obesity and diabetes? We can address that and gas shortages and prices at the same time, by using old-fashioned manpower to get around. By hooking up generators to the stationary bikes and other exercise equipment we use at the home and the gym, so they generate electricity instead of using it up. By building bike-powered drive-in theaters and other such alternative energy solutions. Part of dealing with the energy crisis should include encouraging bike-friendly urban design and rules of the road. Hybrid and electric public transit as well as personal cars.
There are a lot of things they aren't talking about. So go call them on it!
(you can contact the McCain campaign here).