Already exists in the form of the study hall.
From what I remember about the study hall, 1) there aren't any mic's and 2) the chat is just for a few minutes in between pomodoros. Perhaps it'd be useful if users could easily see who's online and chat about an article or something like that.
I think it'd be a good idea to keep a list of the ways we'd like to see LessWrong improve, sorted by popularity. Ie. email alerts for new responses.
So if you have an idea for how LessWrong could be better, post it in the comments. As people up/downvote, we'll get a sense for what the consensus opinions are.
I think there's a pretty good amount to be gained by improving LessWrong.
Note: I say "ways to improve" instead of "features" because "ways to improve" is more general.