Since everyone else has an opinion on this, I’ll make it brief: Three ways to vastly improve the US economy:

• Federal gas tax. The fuel-efficiency rules recently put in place will spawn lots of innovation into ways to get around them (engine upgrade kits, anyone?). A federal gas tax is easy to apply, forces all automakers to do something with their engines, reduces the demand for transportation (hence, stimulates local production) and reduces dependence on foreign oil and foreign loans.
• Federal calorie tax, to apply not just to sugar-sweetened drinks (again, something that encourages all kinds of fiddling), but to any high-caloric, non-nutritional food substance, including high-fructose corn syrup. America is dangerously overweight, and one reason is that good food is expensive and junk food is not only cheap, but in many cases subsidized. Taxing to reduce the consumption of obviously bad and unnecessary stuff makes all kinds of sense. I am less certain whether it makes sense to subsidize the good stuff – too much bureaucracy, and too many discussions.
• Encourage house-buying immigrants. Granting VISAs to a million families or two, provided they buy a house, should be a much needed shot in the arm. The USA is not even close to being overpopulated, and a fresh new crop of resourceful immigrants is just what the doctor might order. Get to it.

There, that was easy. The rest is a small matter of implementation, which I will leave as an exercise for the reader.

And, as Piet Hein said, if you take humor only for laughter and seriousness only seriously, you have misunderstood both….