We've been running a series of experiments to find a solution to good stories failing to achieve liftoff from /newest.
The latest experiment involves emailing submitters when we notice a good story that got overlooked and inviting them to repost it. (On HN, a small number of reposts is ok when a story hasn't had significant attention yet; see the FAQ.)
Such reposts get an initial upvote from us. They also go into a pool from which the software periodically selects a story to place randomly near the bottom of the front page. Not all such stories get this treatment—it depends on factors like how old they are, how stale the front page is, and some randomness.
Placing a story near the bottom of the front page ensures that it gets a bit more attention from the community—surprisingly less than expected, but still a lot more than languishing on the 5th newest page. If there's interest, the story rises; if not, it falls off after a few minutes.
We use a combination of software filters and human review to find good-but-overlooked stories. "Good" here means by HN's definition of "gratifying intellectual curiosity".
The currently open questions are: (1) what to do when the submitter has no email address or doesn't check their email; (2) whether to add a profile setting people can turn on to have this happen automatically, and how exactly that would work; and most importantly (3) how to distribute the human review aspect to the community in a way that doesn't just reduce to the upvoting mechanism, which obviously does not suffice to surface the best stories.
Here are some links to look at if you want more about this:
https://hn.algolia.com/?sort=byPopularity&prefix&page=0&date... (<-- mostly comments I posted because the submitter had no email address in their profile)
https://news.ycombinator.com/item?id=9828818