I ran across this and thought it may be of interest. This was mentioned in passing in a couple of threads already, but it hasn't received any further comment.
rbutr is a community driven app which creates links between webpages where the content of one page is a rebuttal against the other. The content may be directly arguing against the original content, or generally presenting contradictory evidence. App users are alerted when they browse a rebutted page, providing them a link through to the rebuttal(s).
rbutr aims to facilitate inter-website debate, guide users to rebuttals of dubious information, and indirectly influence our users so that they approach all online information with an increased level of skepticism and critical appraisal.