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.

Fides IT

Post Category Gallery displays all non-empty post categories in a horizontal list, graphically displayed as buttons. The categories can be selected such that the posts shown below it are filtered. For each post, the featured image is displayed. The post thumbnails link to the posts themselves.
<a href="http://www.fides-it.nl/post-category-gallery-plugin/" rel="nofollow ugc">Download the plugin from my website , as well as the screenshots</a>
<h4>Features</h4>
<ul>
<li>Three different color schemes: brown, green and blue</li>
<li>Categories can be excluded or included</li>
<li>Configurable thumbnail size</li>
<li>Show category count or not</li>
<li>Re-uses the parameters from the standard wp_list_categories template for the categories list. </li>
<li>Caption of post shown above or below each featured image</li>
</ul>

Post Categories Gallery

Post Category Gallery displays selectable categories of posts horizontally and below the featured images of selected posts are displayed.

azurecurve Floating Featured Image vs Post Categories Gallery