ognjen.kuljic

Some very useful plugins like Regenerate Thumbnails leaves old files behind, so it is good practice to clean after it.
Features: 
*Remove all unused files from upload dir (Unattached files to posts or pages), 
*Remove all leftover files (forgotten files in upload dir).

qCleanup

This plugin allows you to delete unused and leftover files from upload dir. In one click you can rid of all unwanted files and reduce space usage.

Stanislav Khromov

DamirCalusic

WP Users Media works right away when you activate the plugin. No more settings needed. If you need the options switched on for the Admin also you can do it in the Options Page located in the Settings area.
What the plugin does is to disable the ability for users to access other members files and attachments through the Media Button and Featured Image sections. This is really good because maybe you have Authors, Contributors and Subscribers that write posts etc. and you do not want them to be able to use other members media files to their own content.
To test it out create <code>3 users</code>, <code>1 Admin</code> and <code>2 Author's</code> for an example. As Admin you are able to see all media files from all the users on the site.
<ol>
<li>Upload some photos or other media files as Admin. Log out</li>
<li>Login as <code>Author 1</code> and click on the Add Media button for an post or a page. Now you do not see any media files at all. If the plugin was inactivated you would be able to see the photos that the Admin uploaded. Now, upload some photos as <code>Author 1</code>. Log out.</li>
<li>Repeat step 2 for <code>Author 2</code>. As you can see <code>Author 2</code> cannot see the files uploaded from the Admin and from the <code>Author 1</code>.</li>
</ol>
This is very effective solution to keep the media files more private.

WP Users Media

WP Users Media is a WordPress plugin that displays only the current users media files and attachments in WP Admin.

qCleanup vs WP Users Media