I experimented with automating something this in a side project by scraping any outbound links on a submitted url - for articles and blog entries those tend to point to references or related material. It works moderately well, but spam links and login links are a problem.<p>Hacker News could add something like that, and attach it to whatever code is being used to vouch for dead comments, so users could upvote the relevant ones. Combined with something to auto-merge similar stories, you might be able to tease out a decent web of context from posted material alone.