While it may seem rather morbid, it is nevertheless a truism to say that death often constitutes one's crowning contribution to mortal society. (Take Jesus, or Samson, for instance.) You just aren't around to observe the fallout.
This obituary from the Economist chronicles some of Friedman's stands and successes, and provides a nice biographical sketch. Friedman authored several books which have quickly become classics in economic literature: Capitalism and Freedom, Free To Choose (with his wife), and Monetary History of the United States (with Anna Schwartz). He appeared last year on Charlie Rose; and it is inspiring to watch him, at 93, reflect on the meaning of his life and existence in general. He comments sagaciously on historical events and personages, current trends, the replacement of Federal Reserve Chairman Alan Greenspan with Ben Benanke, and the state of the international economy. Fascinating in the highest degree.