Put giant mirrored and radio telescopes on the dark side of the moon to stimulate the science&mathematics job glut our country is facing. Too many graduates who were trained for the sciences are flooding the rest of the job market and making unemployment worse.
By setting ourselves a long-term "stretch" goal like the original moon landing America can make a solid move in the direction of a sound economic recovery while setting an example for the rest of the world as to what this country is capable of when we set our collective sights on something.
This ultimately should be a step towards establishing a base on the moon as well. If we ever want to get people on mars we can't be skipping stepping stones along the way there.