Brad Williams

This plugin will display all themes located in wp-content/themes on a page or post in a showcase gallery with theme screenshots and preview links. 
This is a great plugin for designers looking to showcase their work or anyone that wants an easy way to display and preview multiple themes.
New settings page allows you to choose which themes are displayed
For support visit our Theme Showcase Support Forum: 
http://webdevstudios.com/support/forum/wordpress-theme-showcase-plugin/
Features:
<pre><code>* Display a showcase of your themes
* Theme screenshots are displayed with titles and descriptions
* Easily preview all themes loaded in WordPress
* Allow anyone to preview themes, not just administrators
* Works with both WordPress 2.x and WordPress MU (2.7 approved!)
* New settings page lets you pick which themes are displayed
</code></pre>
<h3>Plugin Support</h3>
<a href="http://webdevstudios.com/support/forum/wordpress-theme-showcase-plugin/" title="WordPress Plugins" rel="nofollow ugc">WordPress Theme Showcase Support</a>

WordPress Theme Showcase Plugin

Display themes located in wp-content/themes on a page or post in a showcase gallery with theme screenshots and preview links.

themifyme

Themify Portfolio Posts is a simple plugin that allows you to showcase your projects info in a clean layout. Minimal and sleek, you can click on each image of your gallery portfolio and opt to show further details such as the project type, client name, and commission date – or edit each heading and name your own.
Themify Portfolio Post plugin is compatible with any theme and users can install it on their WordPress admin dashboard like all other plugins.

Themify Portfolio Post

Add a simple Portfolio post type to your site.

WordPress Theme Showcase Plugin vs Themify Portfolio Post