Change the tuition structure for public colleges and universities such that students pay a percentage of their income (i..e 5%) back to the college for a set period of time. To make administration easy, have the IRS collect the money via payroll deductions and forward it to the schools. Allow each school to set their own terms (i.e. percentage rates, years of repayment).
This would eliminate a student's finances as a barrier to entry for a university, and tie a school's income to the success of its graduates, creating incentives for the school to better prepare students for future careers.
An article describing a similar proposal can be found here: http://usatoday30.usatoday.com/news/education/story/2012-02-02/californi...