Tobias Nyholm

Prevents an user to publish a post without a thumbnail. If a user presses the publish button without a thumbnail, the post will 
be saved as a draft. For more information see installation page or the 
<a href="http://www.webfish.se/wp/plugins/require-thumbnail" title="Webfish - WordPress plugin" rel="nofollow ugc">Webfish</a> homepage.

Require Thumbnail

Prevents an user to publish a post without a thumbnail.

bjovaar

Plugin for WordPress that the add thumbnail image from post in the post and page list in admin area.

Show Thumbnail Image In Admin Post / Page List

Used this plugin twice so far and it does exactly what its supposed to, it just works and its perfect what what i was trying to achieve.

Just Works!

STIAP Plugin for Wordpress that the add column for thumbnail image from post and page in the post / page list in admin area.

Require Thumbnail vs Show Thumbnail Image In Admin Post / Page List