title: django-admin: Add extra row with totals
body: <p>I'm using the standard django admin module to display a list of rows. One of the columns is a numerical field. I'd like to display an extra 'totals' row that has most of the columns as blank, except for the numerical column, which should be the total for all of the objects.</p>
  
  <p>Is there a simple way to do this within the admin module, or am I better off making a custom view for it?</p>
  
  <p>I'm using Django 1.2.</p>