This personal account plan from the Cato Institute received great praise for the Social Security Administration:
http://www.cato.org/pub_display.php?pub_id=3741
"According to SSA's actuaries, the 6.2 Percent Solution would eliminate Social Security's long-range actuarial deficit and restore the system to permanent "sustainable solvency." The legislation compares very favorably to other Social Security reform plans. In terms of giving workers more control and ownership of their retirement funds, the 6.2 Percent Solution clearly provides the most "bang for the buck." By 2046, the system would begin running surpluses, allowing any short-term debt to be repaid. Indeed, by the end of the 75-year actuarial window, the system would be running surpluses in excess of $1.8 trillion (in constant $2005)."
That's the boring summary. And the interesting summary: the bigger the personal account, the more money we retire with!
-Andrew Ward