Community member Itsananderson recently published a link on the forum to a blog post he wrote explaining how to use Pages in WordPress to allow end users the ability to edit their 404 template page with the Page editor instead of manually editing a 404.php template file. Like Anderson’s post title, this enables even your Grandma to manage 404 error pages within WordPress.
I have yet to come across a theme which uses this method to edit template files although I wonder how useful it would be for template files outside of the 404 page? Have you seen private pages used in this way before?
I use that method in a theme of mine, but it isn’t for WordPress. Nonetheless the concept is a good one.