Perhaps you could train a Bayes classifier on users' voting patterns (beginning with a corpus of good and bad comments) and use that to a) decide how to weight

Perhaps you could train a Bayes classifier on users' voting patterns (beginning with a corpus of good and bad comments) and use that to a) decide how to weight users' votes and b) classify further comments as good or bad. (This makes no attempt to classify comments by their content--that'd be done in the construction of the original corpus.) Cf. http://news.ycombinator.com/item?id=2404283 http://news.ycombinator.com/item?id=2404283, http://news.ycombinator.com/item?id=2404459 http://news.ycombinator.com/item?id=2404459