Marcus Downing

Adds an “Identifier” column to the All Posts and All Pages admin panels, and to any custom post types. 
This column goes just after the Title column and shows each page’s slug, indented if necessary.

Page Identifier Column

Adds an "Identifier" column showing a post of page's slug, just after the Title column.

RPG84

On edit.php you will be able to see the currently used featured image for a post. Now you don’t have to open a post to add a featured image. You can do this from the edit.php screen.

Easy Featured Image

Easily edit and see featured images on your post edit screen.

Page Identifier Column vs Easy Featured Image