I explain what I've learned from creating and judging thousands of predictions on personal and real-world matters: the challenges of maintenance, the limitations of prediction markets, the interesting applications to my other essays, skepticism about pundits and unreflective persons' opinions, my own biases like optimism & planning fallacy, 3 very useful heuristics/approaches, and the costs of these activities in general.
Plus an extremely geeky parody of Fate/Stay Night.
This essay exists as a large section of my page on predictions markets on gwern.net
: http://www.gwern.net/Prediction%20markets#1001-predictionbook-nights
I would expect Krugman to suffer penalties over the last few years; I don't read him very much, but he seems to have gotten much more partisan and inaccurate as time passes.