A build-in plugin manager that would allow you to turn plugins on or off AND clearly specifies the correct versions of the installed plugins. After restarting Pro Tools your plugins would then be turned on or off according to the settings you made in the plugin manager.
It would be fantastic if it could be done WITHOUT a restart of Pro Tools, BUT even if i do have to restart Pro Tools this would make such a difference with troubleshooting (also a great help for Avid's support department). Also in classroom situations this would make such a huge difference when having to check wich plugins and versions are installed.
I prefer to have it build into PT but even a well programmed standalone Utility with a clear interface would be such a time and life saver.