chrisguitarguy

Note: This plugin requires <a href="https://wordpress.org/extend/plugins/posts-to-posts/" rel="ugc">Posts 2 Posts</a>
Allows you to associate a custom post type (“slides”) with any of your other post 
types (defaults to “pages”). This is useful for theme developers of those that 
want to add custom sliders around your theme.
This plugin does not provide you out of the box front end functionality. If you’re 
looking for a drop in and play slider, this isn’t it.

P2P Slides

A slider that uses Posts 2 Posts to associate post types with a new, custom slide post type.

asimeon

With this widget its easy to have relations between posts, depending on their category.
You can create category-relationships on back-end and have an easy widget on front-end. See or remove existing relations between the current post or add a new.
<ul>
<li>All actions are user-role-controlled. It means only users who are allowed to edit the current post, are allowed to edit the relation.</li>
<li>The relations are stored in the WordPress database</li>
<li>
Easy undone deleting changes
Example:
Create a relationship between the categories movies and actors. On front-end add actors playing in a movie.
</li>
</ul>
<h3>Issues</h3>
<ul>
<li>delete exisiting relation in backend-config</li>
<li>forward/backward buttons in search/relations-list</li>
<li>create post / search post</li>
<li>deinstall hook</li>
</ul>

Post Relation Widget

With this widget its easy to have relations between posts, depending on their category.

P2P Slides vs Post Relation Widget