django-user-creation is an app that overrides the admin so that when you create users, you can easily email them a link to activate their account, or their credentials, if you choose to provide those for them.
Install django-user-creation into your python path.
Copy the contents of templates to a template folder in your project
Adjust the activation_subject.txt and activation_email.txt to your wishes
Append 'user_creation' to your INSTALLED_APPS setting
Add from user_creation import useradmin in you root urls.py after admin.autodiscover()
# user_creation (r'^accounts/', include('user_creation.urls', 'user_creation', 'user_creation')),``
to your root urls.py. You can change the base url ('accounts/') to something different if you want. Note that it only contains a suburl 'activate/', so even if you have other stuff included at 'accounts/', you should be fine.
If your templates don't extend a main template called base_site.html, adjust activate.html accordingly.