Roth and Shapley win the 2012 Nobel Prize in Economics

. . . "for the theory of stable allocations and the practice of market design."

Alvin Roth, from Wikipedia:

Roth has worked in the fields of game theory, market design and experimental economics. In particular, he helped redesign mechanisms for selecting medical residents, New York City high schools and Boston primary schools.

His work on kidney exchange is fascinating:

Roth is also a founder of the New England Program for Kidney Exchange along with Tayfun Sonmez and Utku Unver,[16] a registry and matching program that pairs compatible kidney donors and recipients.[17]

The program was designed to operate primarily through the use of two pairs of incompatible donors. Each donor was incompatible with her partner but could be compatible with another donor who was likewise incompatible with his partner. Francis Delmonico, a transplant surgeon at Harvard Medical School, describes a typical situation,[18]

Kidney exchange enables transplantation where it otherwise could not be accomplished. It overcomes the frustration of a biological obstacle to transplantation. For instance, a wife may need a kidney and her husband may want to donate, but they have a blood type incompatibility that makes donation impossible. Now they can do an exchange. And we've done them. Now we are working on a three-way exchange.

Because the National Organ Transplant Act forbids the creation of binding contracts for organ transplant, steps in the procedure had to be performed roughly simultaneously. Two pairs of patients means four operating rooms and four surgical teams acting in concert with each other. Hospitals and professionals in the transplant community felt that the practical burden of three pairwise exchanges would be too large.[19]While the original theoretical work discovered that an "efficient frontier" would be reached with exchanges between three pairs of otherwise incompatible donors, it was determined that the goals of the program would not be sacrificed by limiting exchanges to pairs of incompatible donors. Recently, however, a twelve party (six donors and six recipients) kidney exchange was performed in April 2008.[20][21]

Shapley, photo from Wikipedia

Lloyd Shapley, from Wikipedia: 

He has been instrumental in the development of utility theory, and it was he who laid much of the groundwork for the solution of the problem of the existence of Von Neumann-Morgenstern stable sets.  

Roth's webpage is here, and a short description of Shapley's work is here.  
Here it is more form Marginal Revolution.