dexxaye

This plugin allows user to add additional columns to admin posts and pages page. 
Now supports custom post type

Custom Admin Columns

This plugin allows user to add additional columns to admin posts and pages page.

shazdeh

This plugin adds two options for widgets, one to set the width of the widget and also an option to show an icon beside the widget. You can define new rows of widgets using the Divider widget. Supports RTL layouts as well.

Widgets in Columns

Using this plugin you can show your widgets in desired columns and rows. You can also display an icon beside the widget.

Custom Admin Columns vs Widgets in Columns