Two components to this plugin. I haven’t tested the “admins must approve all user signups” nor been on the receiving end of flag notifications, so maybe #1 is done already.
- Moderators & admins get a “Mod Queue” added to their profile.
- Admins can select all kinds of automatic actions to go through this queue for approval.
- Leader promotions (see this and this.
- Certain types of badges
- Title changes by Leaders
- New tags added (see this)
For rare occurrences, I think this could work well. For instance Leader promotion happens rarely enough that it might as well require one last OK from a human, which also forms a stronger bond of trust if the promotee know that’s required. Same for badges.
Things like title changes and tags are trickier though, since these are actions that benefit from immediacy. In their case it might work better to add them pre-approved to the queue, available for quick disapproval when deemed necessary.