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.

Phoenix Online

This easy-to-use plugin allows you to quickly and easily edit post meta values for almost any post type (including custom post types)
Edit post meta as plain text, in textareas, as light-weight HTML or using the full WordPress WYSIWYG editor!
From the first version, this has been designed for ease of use by site Contributors and Editors, but keeps settings reserved for Admin’s only. This gives site Adaministrators control over what less-privileged users can bulk edit.

Bulk Postmeta Editor

This plugin makes it easy to check and edit serialized data in a targeted and comfortable way. Both custom fields and hidden meta data can be easily queried by post type. The plugin then lists all data in an editable input field of your choice which makes comparing and editing the data a breeze.  


Very helpful for debugging

Allows you to bulk-edit post meta information (including custom post types) from a single place.

FD Word Statistics Plugin vs Bulk Postmeta Editor