azurecurve

featured-image shortcode allows a floating featured image to be placed at the top of a post. Default settings can be entered to simplify the use of the plugin.
When used several parameters are available for use: 
1. image – to use an image other than the default 
2. title – set a title on the image (will appear in the tooltip) 
3. alt – enter the alt text for when the image cannot be displayed 
4. taxonomy – enter a category or tag name or slug to have a hyperlink added to the image 
5. is_tag – set to 1 for when the taxonomy should be a tag instead of a category
This plugin is multi-site compatible.
This plugin supports language translations. If you want to translate this plugin please sent the .po and .mo files to wordpress.translations@azurecurve.co.uk for inclusion in the next version (full credit will be given). The .pot fie is in the languages folder of the plugin and can also be downloaded from the plugin page on http://development.azurecurve.co.uk.
Current translations: 
Serbian (sr_RS) translation by Borisa Djuraskovic of <a href="http://www.webhostinghub.com/" rel="nofollow ugc">Web Hosting Hub</a>

azurecurve Floating Featured Image

Shortcode allowing a floating featured image to be placed at the top of a post; this plugin is multi-site compatible.

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.

azurecurve Floating Featured Image vs SSM Xtra Post Info