Hey, this is a project I've been working on. The homepage has a demo of what the sidebar looks like (which overlays to the right of your browser when you open the extension). Feedback/questions appreciated!
I hope this feature request would be useful to you.
Thanks for the suggestion! I'll look into it. I am wary of asking permission from host sites because then it's not necessarily user controlled (plus there wouldn't be a huge difference between us and something like Disqus). There are potentially ways I could integrate things like host verification for comments though.