Ron Lieber:

The biggest problem for consumers of American higher education is that many of them must take on a mountain of debt to get the degree they want. That intimidating quandary has inspired some unique, though often unsuccessful, attempts to make student loans more affordable over the years.
One of the most innovative sprang from a handful of trailblazers, including an economist who later won a Nobel and some entrepreneurs barely out of school themselves, who tried to persuade undergraduates to sell a portion of their future income to investors in exchange for money for college. Critics fretted about “indentured servitude,” and the idea never amounted to much.
Others have tried to let strangers finance students’ fixed-rate loans via Web sites. The idea of “peer to peer” lending hasn’t gained much traction either so far.