Here are two major problems that can be solved with one simple program.
Problem #1) The American Public is notorious for not saving.
Problem #2) It is hard for The American Public to find a safe place to invest its money.
The United States Government can solve both of these major problems by issuing endless (no maturity date) 6% Citizen Savings Bonds that can only be purchased by American taxpaying citizens in order to (a) encourage saving by the public and (b) give the public a safe place to invest their savings, thus supplementing (over time) (c) Social Security, (d) medical insurance, (e) money for college and (f) money to buy a first-house.
Since the United States government can always create whatever money it needs for worthwhile programs, the cumulative interest earned on these bonds would not, in any way, interfere with the government's ability to run it's day-to-day operations.
Having a safe place to invest savings would be a huge boon for taxpaying citizens who are not really geared to analyzing various investment and insurance programs.
The bonds would run with no maturity date. The citizen taxpayer would be allowed to cash the bonds in at any time -- suffering a 20% penalty for doing so within the first 5 years of buying the bond.