Bill Erickson

Gary Jones

Customizing the contents of the Page Not Found page in any WordPress theme can be tricky, and usually involes editing the 404.php template file. The Genesis Framework already abstracts the default content of the page into a function, and this plugin can unhook that and replace it with your own custom title and content.
Use [genesis-404-search] shortcode to add a search form to the page.
If you’d like to dynamically list content (ex: most recent posts), I recommend you install the <a href="https://www.wordpress.org/extend/plugins/display-posts-shortcode/" rel="nofollow ugc">Display Posts Shortcode</a> and use it in the 404 page’s content.

Genesis 404 Page

Customize the content of the 404 Page within the Genesis Framework.

Ron Rennick

marksabbath

Nathan Rice

StudioPress

Nick the Geek

The AgentPress Listings plugin uses custom post types, custom taxonomies, and widgets to create a listings management system.
You can use the taxonomy creation tool to create your own way of classifying listings, and use those taxonomies to allow users to search for listings.

AgentPress Listings

This plugin adds a Listings custom post type for Real Estate agents.

Genesis 404 Page vs AgentPress Listings