Widget areas are great opportunities to stimulate content discovery on your site. The featured image gallery widget makes this process visual, automatically showing the featured images for all of the posts on a given view (archives, taxonomy terms, etc.) in one place. The widget is only displayed on views with multiple posts, and uses the same styling as the core gallery widget.
Two-column featured image gallery widget in a custom theme’s sidebar.
Three-column featured image gallery widget in the Twenty Fourteen theme’s content sidebar.