BuddyPress Registration Groups is a plugin that adds a list of groups to the registration form so that new members can be introduced and join your groups. It means they don’t need to go looking for them to be instantly tied in to their preferred groups. Adding this kind or form to your registration can help you to build a profile for each new member.
GR Dashboard notes, whilst not being specifically a BuddyPress plugin could be useful for membership sites with a few admin and moderators. This plugin allows you to add notes to the dashboard that will only be seen by members of specific roles. So for example it could be used to send a general note to all admin, and they’d see it as soon as they visited the dashboard.
LH Logged In Post Status is a WordPress plugin that adds a new post status of “Logged In” to the available status options in the Publish dialogue box. What this means is that posts can be published only to logged in users, which is an option that would enhance the privacy options available for post content.