It would be very useful and sometime a necessity to manage another users account.
The elements that would be needed are.

1. Notification
2. Drafts
3. Workflow

--Notifications
The ability to see others users notifications and clear then or modify them

--Drafts
The ability to see other users drafts and clear then

--Workflow
See other users tasks in workflow and reassign them to another user of complete them from the superuser.

These are all really useful when someone if off ill or leaves a company.