I would eliminate the difference in tax rate for capital gains income - or even tax capital gains at a higher rate than other income. Not doing that simply to get more revenue to the govt., but to eliminate the unnatural incentive that exists for the brightest, greediest and most ambitious to ALL go into the financial industries. In those industries, all of that talent goes into coming up with novel ways to attract more wealth to themselves. Were that area not SO attractive (because income from there is not taxed at a lower rate), eventually some of those people would head back out into other fields, and possibly put that greed, intelligence and desire into pursuits that, as a byproduct of making the individuals rich, also actually increases the size of the economy. Certainly not a quick fix, but something that structurally could have long-range benefits.
Also, for more immediate impact would begin large-scale reconstruction/repair of infrastructure (roads, bridges, dams), including adding/expanding to the interstate highway system. Put a bunch of people to work building - train them to do it, if necessary; get them off their asses before we have an impossibly large, permanent, dependent class.