Ahmad Karim

This plugin will display related posts in your 404 page template. The related posts will be displayed based on the invalid URL user visited. It will check against the post types saved in the settings and will look for similar posts which match the URI.

404 Related Posts

This plugin will display related posts in your 404 page template.

stephenblender

The Related Links Blender plugin to makes it easy to cross link your posts and link to external web pages. Your visitors will be provided with hand picked topical reading options at the end of the current post. Search engines will see more carefully SEO crafted content.
Related links are selected and defined on a post’s editor page in a custom panel. These links are added for viewing at the end of a post’s or page’s content.
Construct a link using the tools in the Related Links Blender post edit panel. Use the FIND A POST tool to search through your existing posts to quickly create rich links, or manually enter a link to any webpage you want. Links are pre-compiled for efficient display. This is the preferred way to add links – tuned for visitor’s interest and SEO.
The Related Links Blender plugin has a settings page in which you can customise how the inserted links are constructed and styled. This requires some basic HTML knowledge.
NOTES
<ol>
<li>This plugin is a beta release that is under development. Please report any issues!</li>
<li>This plugin is intended for advanced users and not documented for causual or beginner users</li>
<li>Want to send a donation?: http://blender.ca/payment</li>
</ol>

404 Related Posts vs Related Links Blender