Peter Westwood

This plugin allows you to configure extra mime-types for support by the inline-uploader.
A new options page is added as Options … Mime-types which allows you to add/delete the extra mime-types.
By default the following extra mime-types are registered: audio/ac3, audio/MPA and video/x-flv.
With version 0.90 of the plugin you are now able to upload a file containing a long list of mime types as an easy way to register multiple mime-types. 
The file format is “mime/type extension” for example like this:
<pre><code>audio/ac3 ac3
audio/MPA mpa
video/x-flv flv
</code></pre>

PJW Mime Config

This plugin allows you to configure extra mime-types for support by the inline-uploader.

arthurlacoste

Add more files extensions with a new field in your Medias Settings.
<a href="http://irz.fr/add-more-files-extensions/" rel="nofollow ugc">You can check the dev page</a>
You just need to insert your extensions in <code>Settings > Medias > Uploading Files</code> separate by a space (ex : ‘exe pdf rar’), and the plugin does the rest.
This plugin is in french but the translation in english is in progress.

Add more files extensions

Add more files extensions with a new field in your Medias Settings.

PJW Mime Config vs Add more files extensions