Access Denied Backtrace will help you track down the specific place where Drupal is triggering the access denied for a certain role.
Use Case:
Have you ever gone crazy when certain roles cannot access nodes in Drupal? Then you have to start checking permissions on and off just to finish right where you were to begin with? Or even worse get some more permissions control modules so they can override Drupal permissions.
The Topbar Message module allows the administrator to add a configurable Topbar Message to the page. Display can be set either as site wide or controlled via the context module.