1. For the 'reply' button under each post on a thread to have a specific function.
For example, for the post that you wish to reply to to automatically be quoted in your response, without you having to cut and paste. That or a 'quote' button that makes the text of a particular post (or of several posts) appear in your reply,
2. For a 'like' button.
To my mind, it is both the easiest and the least cliquish way of expressing one's agreement with what another poster has said.
3. An edit button.
I know it would sometimes mean that people respond to a post that has since been removed or edited, but we are adults and could cope with it, as people do perfectly well on every other forum I have ever used.
When I started typing this, I had a fourth thing in mind too, but it's slipped my mind for now!
Irritating personality traits haven't softened - do friendships change?
Needed but feeling left out - do others feel the same?
Where were you on this day? - moon landing