Looking for a bulletin board plugin integration WP comments

Hi,

I want to centralize all the WP post comments in a bulletin board on my site. With the possibility to answer to comments (which should be shown below the related post, too) and to start new discussions which are not related to a post.

Is there a WP plugin for this? Or are there other ideas? I have a lot of posts (local news), and it's hard to find all the user comments.

Thanks,
Martin