Louy Alakkad

This plugin gives you the ability to run the site in a language (Arabic for example) and use the admin panel in another (like English).
Just go to Settings » General and choose your language.

Admin Locale

This plugin allows you to change the language of the admin panel without changing the whole site language.

codycode

Do you ever go to other sites, seeing people comments and don’t understand what they are saying? Ever feel lonely because not understand people. 
With Comment Translator, people will get closer :D.
Features: 
 – Layout customize fit to your sites 
 – 2 appearances 
 – 3 translate engine (Google, Bing, Yandex) base on your need 
 – 4 Language picker positions
<h3>A brief Markdown Example</h3>
Ordered list:
<ol>
<li>Layout fit to your sites</li>
<li>2 appearances</li>
<li>3 translate engine (Google, Bing, Yandex) base on your need</li>
<li>4 Language picker positions</li>
</ol>

Comment Translator

Help your visitor translate other comments to their language

Admin Locale vs Comment Translator