A Swiss Army Knife for WordPress developers. Enter a slug or id, select a template you created, and it will render the content with your template.
This is what you'll see when you place the widget. Title is the same as other widgets, I usually leave it empty. Slug or id is the identifier of the page or post you want your template applied to. The slug is the last part of the url of the page or post. Subtemplate is the template you have created according to the instructions available on the instructions page.
Since version 0.4, the widget will detect if you've entered a slug that doesn't exist.