A possible mechanism for this is the "favorite" link that you can get to by clicking on the timestamp of a comment. Currently, I don't think much is being done

A possible mechanism for this is the "favorite" link that you can get to by clicking on the timestamp of a comment. Currently, I don't think much is being done with it other than adding it to a private per-user list, but it could also be used to highlight or boost the chosen comments? A quick fix might be to just add another item to the "Lists" link at the bottom that shows the top "Favorited" comments, based on how many people have it as their most recent (or 10 most recent) favorite.