One thing that hacker news does that I really like is seemingly randomly bumping up certain comments to the top, temporarily. They are likely doing this based on the number of interactions the comment has received. Crucially, it doesn't always happen and you often can't even tell it's happening, since it looks like just another top comment.
This solves a number of problems:
- it brings possibly counter-circlejerk opinions to the top (and makes people actually read them seriously, since they are at the top where they expect a high-rated comment to be)
- it causes less "freezing" of the comment hierarchy over time
- it gives users the chance of making comments that get read and voted on, even if they are late to a thread.
- it raises the long tail of high-quality comments. Usually, there are a few high-rated comments, and a large "swamp" of both good and bad comments with little views after that. This feature would likely increase the number of good comments that get out of the "swamp", while also increasing the number of low-quality comments that get flagged as such.