Nick Ciske

Makes media library thumbnails match the WordPress thumbnail size or allows you to choose a new size in Settings: Media (or hard code a custom size named ‘mte_thumbnail’).
Also replaces the default “Crystal” file type icons with smoothly scaling SVG icons that better match the WordPress 3.8+ design.

Media Library Thumbnail Enhancer

Enhances media library thumbnails by making them larger and replacing the bundled icons with scalable SVG versions.

Chad Hovell

Select extra layouts from the post editor Screen Options menu. 
There are now 24 variations to choose from!

Three Column Screen Layout

Three, four and five column screen layouts for the post editor.

Media Library Thumbnail Enhancer vs Three Column Screen Layout