__init__.py

from .base import *
try:
    from .local import *
except ImportError, exc:
    exc.args = tuple(['%s (did you rename settings/local.py-dist?)' % exc.args[0]])
    raise exc

local.py-dist

# example to extend things
#import base
#INSTALLED_APPS = base.INSTALLED_APPS + ('django_debugtoolbar',)

DATATBASE = {
...