>This is a cool idea. I would install a Chrome extension that shows a score by every username on this site grading how well their expressed opinions match what subsequently happened in reality, or the accuracy of any specific predictions they've made.

Why stop there?

If you can do that you can score them on all sorts of things. You could make a "this person has no moral convictions and says whatever makes the number go up" score. Or some other kind of score.

Stuff like this makes the community "smaller" in a way. Like back in the old days on forums and IRC you knew who the jerks were.