As a beginner of discourse, there seems to be too many plugins and most of them are non-default. Truely I think some of them are fully-developed (you know, no bugs and very helpful. ) and can improve the forum service very much.
But there are still many plugins that are only an idea hoping for suggestions are many plugins useless—— or we say not for most of the forums.
So I think we should maintain a list of plugins recommended. And let the plugin developers to apply for entering such list. We can also vote for the best plugin for the month and then the winner plugin would enter such list. You know, for fun and encourage developers.