bmeisler

This is a very simple (but useful) plugin. All it does is:
<ol>
<li>adds a “Featured Image” checkbox to the Screen Options when viewing in All Posts mode.</li>
<li>when the checkbox is selected, it will add a thumbnail of the post’s Featured Image to the All Posts screen.</li>
</ol>
This allows you to:
<ol>
<li>easily take an inventory of posts to see which are missing featured images (in this day and age, all posts should have a featured image) and</li>
<li>quickly scan your posts—it’s frequently easier and quicker to identify a post by its featured image than by scanning titles.</li>
</ol>
No css or js is added. The database is not altered in any way.

SSM Xtra Post Info

a must have

A very simple plugin that shows a thumbnail of a post's featured image when you are in the Posts/All Posts view mode.

MD.Ridwan

Plugmint – Sticky Notes for Posts, Pages, Products & CPTs plugin lets adminis to attach short notes inside the post editor. Notes are stored as post meta and are not visible on the front-end.

Plugmint – Sticky Notes for Posts, Pages, Products & CPTs

A lightweight plugin to add private admin-only notes to posts, pages, products and on any custom post types.

SSM Xtra Post Info vs Plugmint – Sticky Notes for Posts, Pages, Products & CPTs