Lets you include another template and pass in named variables. Use like: {% partial field_template field=form.city %} If no key is specified, it will use "item" instead. You may pass in multiple variables as comma-separated key=value pairs.
At WWU Housing, we started using the [Tempest jQuery plugin](http://plugins.jquery.com/project/tempest) for javascript templating, which has the same {{ var }} syntax as Django's templating. We wanted to be able to use the same templates in our server-side python and our client-side js, so we had to have a way of including the unrendered template for the js. At the same time, for convenience, it had to be modular so we could push the same code from our dev- to our live-server and not worry about absolute paths (which is why the {% ssi %} tag did not work). So the {% include_raw %} tag was born.