I have a strong feeling upmod/downmod is broken as a mechanism for guageing the "interesting-ness" of web posts. It seems that everyone agrees that the community "ought to" upmod valuable things and downmod useless things independantly of whether each person agrees or disagrees with the basic premise, however what I observe is that the more emotionally invested someone is in an issue, the further they stray from the utopian ideal.
The problem is overloading a tiny 1-dimensional 'grunt' of a feedback mechanism. (Or really, half-a-dimension, when only upvotes are allowed.) It's aggravated by the fact the exact same up-arrow is an approved way to agree with a comment. [1]
My suggestion when this problem has come up previously: adopt a 2-axis feedback mechanism, with up-down meaning promote-demote (give something more/less attention), and right-left meaning agree-disagree. [2] [3]
The Boston Globe has started including something similar to that in its print newspaper: they have a 2D scatterplot under the Letters to the Editor where the y-axis is the number of letters on each topic and the x-axis is whether the letters were in favor or opposed. It's a nifty at-a-glance visualization.
