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.

Andrey Ovcharov

This plugin adds column with thumbnails featured images for selected post types

WP Thumbnail Column

This plugin adds column with thumbnails for selected post types

Media Library Thumbnail Enhancer vs WP Thumbnail Column