Dartmouth Economics Professor & Director of the Rockefeller Center, Prof. Andrew Samwick along with two other former prominent political adivsors has written a Nonpartisan Social Security Reform plan. The plan involves the creation of private retirement accounts, raising the retirement age faster, and raising the payroll tax cap among other changes and provides a comprehensive plan to save Social Security. Prof. Samwick talks about his plan in this podcast. Full details/text of the plan can be found at the Nonpartisan Plan website.
An additional note, I believe Ariel mentioned this a while ago, but a reminder, Prof. Samwick has his own very interesting blog called Vox Baby.