Greg Mankiw today looks at the h-index.
The h-index is a measure of a scholar’s research productivity. It is defined as the largest number h such that the researcher has published h articles each cited at least h times.
A Wikipedia entry looks at the Top 5 economists based on the REPEC working paper achive. Mankiw looks at the Social Science Citation Index and finds his own ranking lower.
An alternative would be Anne-Wil Harzing’s based on Google Scholar. She has a neat little program (‘Publish or Perish’) that calculates your h-index that is downloadable from here. Using that Mankiw’s h-index is 55 (compared with 34 on SSCI). By the way, my h-index is 14 on Google Scholar and 9 on SSCI; although the latter covers fewer than half my papers. But the latter does a nice graph and you can see that I am on an upswing.