Make it clearer to anonymous / low-rep users that they cannot (yet) add comments
95252
Could new users see a notification in the space where the add comment button would be, like "you need a minimum of X reputation to comment"?
90462
Marking comment as an answer?
70088
Give me a blank Comment box when I am Improving a Suggested Edit
102331
Can we show new/anonymous users more Q&A?
96660
Hide trivial comments
134930
Please make the multiple comment timer less annoying (non-resetting etc.)
41382
Deleting comments under posts in the mod queue should be easier
114749
Allow post editor to see @comments directed at him
149930
Allow moderators to undelete comments deleted by magic words
48377
Commenting out specific environments
20441
Is there a way to edit or delete and reenter comments once they're posted?
38686
Zombie comments (aka wrong comments count when destroying a spammer who posted comments)
110606
Can we get a comments only lock?
114694
Editing old/others' comments
10373
Can we get rid of the threshold of 15 chars for comments?
50262
Please enable low-rep users to easily breakout up and down votes on their own questions
132534
Allow moderators to undelete the comments deleted after being flagged by a single user