AS OF MAY 2016, THIS PLUGIN IS NOT BEING MAINTAINED AND WILL NOT RECEIVE ANY FUTURE UPDATES. 
CONTACT ME IF YOU’D LIKE TO LIST AN ALTERNATIVE HERE.
Shows word and sentence counts plus a readability analysis of the post 
currently being edited using three different readability measurements.
Readability analysis is an attempt to show how difficult a text is to read. 
There are several methods of doing readability analysis. The most popular 
methods are used here. The Flesch and Flesch-Kincaid methods use formulas based 
on the average number of words per sentence and the average number of syllables 
per word. The Gunning-Fog method uses a formula based on the average number of 
words per sentence and the percentage of “hard” words (words with 3 or more 
syllables) in the passage.
Both the Gunning-Fog and the Flesch-Kincaid give a score that is the number of 
years of education the reader must have completed to understand the text. 
Different types of writing calls for different scores. Technical subjects may 
require a higher level of education so a higher Fog or Kincaid score is 
acceptable. Informal writing may try for a score in the 7-10 range. The Flesch 
score is a percentage. The higher the value, the better the readability.

FD Word Statistics Plugin

Shows word and sentence counts plus a readability analysis of the post currently being edited using three different readability measurements.

Globalis

Sometimes happiness is about small things. What about being able to prepare a new version of your content while its original is still online?
Anticipating and preparing the next version of an article which is already online can quickly become a tedious and risky task. Indeed, most publishers will create a brand new post, fill it in, publish it once it’s ready and finally disable the original article.
<h4>Basic features:</h4>
<ul>
<li>creation of a new version of an article in 1 click;</li>
<li>direct access to other pending versions of an article;</li>
<li>update of an article to its new version in 1 click.</li>
</ul>
<h4>Advanced features:</h4>
<ul>
<li>duplication of an article into a brand new independent copy;</li>
<li>hookable 😉 </li>
<li>works with any post types, custom or not</li>
<li>makes coffee (we’re still working on that)</li>
</ul>
<h3>About</h3>
<h4>Hooks</h4>
pnv_duplicata_status_args 
Filter that can be used to alter arguments sent to ‘register_post_status’. 
Default arguments are:
<ul>
<li>
label => Duplicate
</li>
<li>
public => false
</li>
<li>
exclude_from_search => true
</li>
<li>
show_in_admin_all_list => false
</li>
<li>
label_count =>
</li>
<li>
<ul>
<li>singular => Duplicate (%s)</li>
</ul>
</li>
<li>
<ul>
<li>plural => Duplicates (%s)</li>
</ul>
</li>
</ul>
pnv_erase_content_destination 
Filter that can be used to alter $destination array before ‘wp_insert_post’ get called when a copy, duplication or replacement is triggered 
This filter sends 3 other parameters: the $source object (WP_Post instance) and the $copy boolean
pnv_filtered_metas 
Filter that can be used to alter meta names that must not be treated while a post is copied, duplicated or replaced 
The default metas is an array with these values:
<ul>
<li>_pnv_duplicata => true</li>
</ul>
pnv_erase_content 
Action triggered at the end of a copy, duplication or replacement. 
This action sends 4 parameters:
<ul>
<li>
the $source object (WP_Post instance)
</li>
<li>
the $destination array (represents post data)
</li>
<li>
the $copy boolean
</li>
<li>
the destination’s post ID
</li>
</ul>
pnv_action_url_redirect 
Filter that can be used to alter redirect URL after a copy, duplication or replacement. 
The default value is the admin edit page for the destination post (the one that has been saved) 
This filter sends 1 other parameter: the destination post ID 
pnv_{column_name}_column_value 
Filter that can be used to alter the value displayed on the posts list, in the ‘{column_name}’ column. 
This plugin comes with only one custom column for now, ‘duplicata’, so {column_name} will always be ‘duplicata’, and the default value will be the count of duplicates for the post. 
This filter sends 1 other parameter: the post ID
<h4>Thank’s</h4>
The original version of this plugin has been developed by Lionel POINTET (https://github.com/lpointet) who keeps following the project carefully.
A big thank-you to <a href="http://www.groupemoniteur.fr/" rel="nofollow ugc">Groupe Moniteur</a> for which a great part of this development was intended and which accepted enthusiastically to do a completely open source plugin from it. Thank you to <a href="http://uncategorized-creations.com/" rel="nofollow ugc">Uncategorized Creations</a> people, for their regular advice and their perseverance in making WordPress a leading CMS.
<h4>GLOBALIS</h4>
<a href="http://www.globalis-ms.com/" rel="nofollow ugc">GLOBALIS</a> is a web IT consulting company based in Paris, and a pioneer of the PHP and LAMP platform. Since 1997, we have been designing, making and maintaining Internet, intranet or mobile software. We have been working with open source CMS since 2000 and have regularly been using WordPress since 2007.

Prepare New Version

Create the next version of your post while preserving its already online version.

FD Word Statistics Plugin vs Prepare New Version