Provide group admins with an option to set the default access level for group content
Provide link to invite users to group from the manage invitations page
Provide users with an easy way to join a group while browsing content
Let users know they must be group members to participate in discussions, and link to join group
Provide group admins with a method for making group content 'featured', featured content can be viewed on a dedicated page, on the group profile, or in a widget (if using widget manager)
Allow group admins to prevent users from adding blog posts (just removes 'add' button, does not disable adding altogether)