This plugin allows you to write posts in more than one language, all you have to 
do is to add some divs to your posts, each div with a class, that is the 
language’s name. This way your readers will be able to just click in the flags 
and change between languages.

WPMultiLanguageChanger

This plugin allows you to write and you readers to change between languages in your blog in a easy way.

Alexander Rauscha

mLanguage adds Multilanguage Support to your Blog. You have only to write post, tagging each language.
This plugin will not be maintained any longer.
If you want to cantact me anyway, visit http://alexrauscha.com or send me a message on twitter(@gnomx, http://twitter.com/gnomx)
<h3>Features</h3>
<ul>
<li>You have to write only one post/site by tagging the different languages.</li>
<li>Easily switch between the Languages with the Menu without reloading the site.</li>
<li>Only displays default Language in the feed with a note at the bottom that this article is also available in other languages.</li>
<li>Options to add or delete Language Tags or change the default one.</li>
<li>Change Flags in the Options.</li>
</ul>

mLanguage

mLanguage allows you to write your blog contents in different languages.

WPMultiLanguageChanger vs mLanguage