Is the ability to specify a series of template folders in [your settings file](http://www.djangoproject.com/documentation/settings/#template-dirs).

Here’s what we do at [work](http://www.ajc.com):

TEMPLATE_DIRS = (
    os.path.join(os.path.dirname(__file__), "templates"),
    os.path.abspath(os.path.join(os.path.dirname(__file__), "..", "ANOTHERSITE", "templates")),
)

It allows us to easily share templates from ANOTHERSITE with sister/sub sites, but when/if you need to override them you just drop your new template your site’s templates folder and you’re off to the races.

###Another template tip
If you use the tip above, I’d recommend putting templates that are explicity shared in a templates/shared folder.

Then you can do things like:

{% extends 'shared/shared_somethingorother.html' %}

It’s a minor tip, but it helps prevent collisions and alerts developers that these templates shouldn’t have any site specific code in them.