User Status is a Joomla Component.  From the back end, create locations and user records.  Assign users to locations and set their status.  On the front end display the status of users.  Install  the "User Status Update Module" to allow logged users to change their status easily from the front end. Also install "Refresh Page" to refresh the user status display page at regular intervals.  An easy way to visually display who is in and who is out.