Alex

This plugin ensures that there is only one sticky post published to the site. When a new sticky post is published, previous the ‘sticky’ flag is removed from any other posts, so they will no longer appear at the top of your page.
<h3>Important Notes</h3>
<ul>
<li>I adapted code initially found at http://craiget.com/one-sticky-post-in-wordpress/ Thanks to Craige for posting it! Also, Devin Price (http://wptheming.com/) was immensely helpful as I knocked out a couple of issues regarding scheduled sticky posts.</li>
<li>The first time you publish a sticky post after enabling this plugin, any and all other sticky posts will be changed to not-sticky. There is not a way to automatically reverse this decision, nor is their a log of which posts were changed.</li>
<li>This plugin has not been tested with versions of WordPress prior to 4.0.</li>
<li>Do not use this plugin if you are using another to manage per-category sticky posts. It has not been tested with that setup, and it will most likely mark all of those posts as non-sticky.</li>
</ul>

There Can Be Only One

Ensures that there is only one published sticky post on the site at any given time.

jaschaephraim

There are no settings or custom functions. Set custom post types to be sticky just as you would with regular posts, and those post id’s will be included in the result of <code>get_option( 'sticky_posts' )</code>.
PLEASE NOTE In order to integrate as seamlessly as possible, this plugin will not alter any queries or filter any functions. If your sticky posts aren’t appearing the way you want, there’s probably a good reason in your query (Is <code>ignore_sticky_posts</code> set to <code>true</code>? Is <code>post_type</code> set to a different type?). This plugin may be most appropriate for developers who just want the native sticky post UI and no other superfluous features.
If you find this plugin useful, please rate it accordingly.

Seamless Sticky Custom Post Types

Perfect

Great plugin! Hasn't been updated for over three years. But it works great, still!

Still works like a dream

Extends the native sticky post functionality to custom post types in a way that is identical to default posts.

There Can Be Only One vs Seamless Sticky Custom Post Types