Comments should only persist on questions / answers for 48 hours
42721
Self destructing comments
44432
Allow anyone to comment but hide low-rep users' comments until reviewed
129908
Allow flagging own comments
31985
Should a user be forced to add a comment when they vote to close?
20995
Comment status: are they 'disposable'?
63150
No "waiting for review" for comment flags
114102
How to make HTML code inactive with comments
144649
Long comments can break layout
119103
Allow downvoting comments
149234
Stop generating "possible duplicate" comments
51469
Allow converting comments to answers
133230
Why is deleting comments allowed?
44564
Should moderators be able to convert answers into comments?
134399
Automatically hide old comments
138887
Clarify the "8 hour delay" self-answer message to discourage self-answering with edits or comments
107699
When should comments be flagged/deleted on per-site metas?
38709
How to prevent negative comments/downvoted being deleted by re-posting answers