Add new tab in wordpress media gallery

Adding this snippet to the functions.php of your wordpress theme will add a new tab to the featured image popup called mime types. Clicking on this tab will display a list of the allowed file types however this could be changed to display almost any information.

Source: Kevin Chard http://wpsnipp.com/index.php/functions-php/add-custom-tab-to-featured-image-media-library-popup/