I'd like to see a scoring system that evaluates the discussion or thread as a whole, rather than the individual contributions; a metric like a signal-to-noise r

I'd like to see a scoring system that evaluates the discussion or thread as a whole, rather than the individual contributions; a metric like a signal-to-noise ratio, where a thread gets a higher score for being on-topic and relevant, or a lower score for degenerating into a pissing match.