Harvard's Raj Chetty has won this year's John Bates Clark Medal. It's a prize for the best economist under 40 and it normally goes to someone who's ever-so-close to 40, but Chetty got it at the tender age of 33.
He's big into policy-relevant research. Here's a paper he did with co-authors on whether being taught by teachers who are highly rated by value-added testing systems is correlated with good life outcomes that are independent of the testing system. (Yes!) A related earlier paper shows the huge lifelong influence of a great kindergarten teacher. Here's an empirically important paper about dividend versus corporate income taxation he did with Emmanuel Saez where I think they draw the reverse policy conclusion from the correct one (more on this later).
All things considered he's a standout example of the recent praiseworthy trend in economics toward a greater level of interest in obtaining relevant empirical information and using it in a theoretically sophisticated way.
Correction, April 12, 2013: This post originally misspelled Emmanuel Saez's first name.