Auto-populate authorization rights

This will give you the difference between a controller and its parent:
Admin::HomeController.public_instance_methods -

BUT (there has to be one), if the parent controller has a method of the
same name it will not be listed - so the array may be incomplete....

you can use a rake task to pre-populate your database from fixture
files. There are a few reference tables in my system that rarely
change (but are too large to careful of that route; it
can also be very brittle), so this works really well for me.