I'm working a bit on group administration and moderation lately. Here is the latest feature I just added.
If you are a group administrator then you can now grant and revoke user privileges to your group through the group members page.
The menu on the top right will present these new options to group administrators. Be careful who you grant admin rights to, as they would have full power to also remove you from admin! Only a site admin can fix it.
At the moment, moderators still do not have many features available to them since the moderation system is still being developed.
Right now, a moderator can toggle a post NSFW status. More features to come! (and please send requests for features as well).