Fabio M. Giacomini

This plugin adds a new field in every post, where you can write a text that will be inserted in the related meta tag, located in the head section.
The main options page of the plugin, provides you with a default text area, where you can insert a default description that will appear in case the field in post page is empty.

Single Post Meta Description

The easiest way to add in every post page a different meta description tag, located in html head.

FolioVision

Simple plugin which allows you to mass edit the description fields of your choice. In current version of the plugin it is possible to mass edit except the description fields also titles of pages, posts and categories and for posts it is additionally possible to edit keywords
<a href="http://foliovision.com/seo-tools/wordpress/plugins/foliopress-descriptions" rel="nofollow ugc">Support</a>
Supported description fields:
<ul>
<li>All In One SEO Meta Description</li>
<li>Thesis description</li>
<li>WordPress post excerpt</li>
</ul>

FV Descriptions

Simple plugin which allows you to mass edit the description fields of your choice.

Single Post Meta Description vs FV Descriptions