Arefly

Busy with setting every post’s first image to the Featured Image?
Use this plugin instead!
This plugin will auto set the first image of your post (for new posts only) to Featured Image.
If you do not want set the first image, you can still set your own Featured Image.
<h4>How Does It Work?</h4>
You do not need to set anything after you install and no any options.
The plugin will auto set the first image of your new posts to Featured Image.
<h4>How to exclude a specific post?</h4>
<ol>
<li>
Go in to the post/page you do not want to autoset Featured Image.
</li>
<li>
Find Meta Box name “Custom Field”.
</li>
<li>
Click “Enter new”.
</li>
<li>
Enter “no_featured_image” in Name Table and enter anything in Value Table.
</li>
</ol>

Autoset Featured Image

I can see how this would be useful, though, but for my purposes and by the name of it, I was hoping it'd go through old posts and, if they didn't have a featured image, set the first image.



Wish it worked for existing posts...

Auto Set the first image of your post to Featured Image.

voceplatforms

Chris Scott

Adds multiple post thumbnails to a post type. If you’ve ever wanted more than one Featured Image on a post, this plugin is for you.

Multiple Post Thumbnails

Even though this plugin hasn't been updated in a long time, it still works great! So I guess there's just no reason for the developer to have it updated. ;-)
For me this plugin is one of the easiest ways to selectively add a header image. I want it on some pages, but not on others. Using the standard Featured Image function will set it foor all or none, so that's not flexible enough.
One suggestion for an update though:
Now you still need to add the following snippet to your theme's function.php.
if (class_exists('MultiPostThumbnails')) {
    new MultiPostThumbnails(
        array(
            'label' => 'Secondary Image',
            'id' => 'secondary-image',
            'post_type' => 'post'
            'post_type' => 'page'
        )
    );
}
It would be great if the plugin did this automatically. That will also keep the plugin active if you switch themes. 
P.S.
To add the meta box to other post types, just add it to the snippet.
'post_type' => 'event' will add it for Events Manager, for example. ;-)



Still works great!

Adds multiple post thumbnails to a post type. If you've ever wanted more than one Featured Image on a post, this plugin is for you.

Autoset Featured Image vs Multiple Post Thumbnails