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.

Complete Language Switcher is a plugin that allows you to setup your blog with multilingual support.
It also allows you to switch between languages with a nice list of flag which are easily styled.
Complete Language Switcher filters out the posts tagged with a certain language to displayed. Other languages will be hidden in the listings.
<pre><code>Note that this plugin requires the xili-language plugin in order to work.
</code></pre>

Complete Language Switcher

Switch between languages with ease using xili-language plugin. Displaying only the posts in the set language.

Admin Locale vs Complete Language Switcher