Several things I learned the hard way about Django Grappelli.
Sequence of loading the INSTALLED_APPS is very important. The Grappelli module must comes before django.contrib.admin module. Failing to do so and the changes to the admin layout will not take effect.
INSTALLED_APPS = ( 'grappelli', 'django.contrib.admin', )
If you want to customize the layout and use the default CSS styling, read the documentation on templates. Unfortunately, not googlable and must be access locally though your Django instance at http://localhost:8000/grappelli/grp-doc/. Oh boy, so much time wasted on googling for the tutorial or documentation on customization.
Where is the bloody documentation on nav-global block?