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.

ImTheirWebGuy

Provides the ability to select from the classic 1 or 2 column setup on your dashboard in wp-admin. There are no settings, simply install, activate, and then use “Screen Settings” in the main dashboard view to select one or two columns.

Two Column Admin

Provides the ability to select from the classic 1 or 2 column setup on your dashboard in wp-admin.

Custom Admin Columns vs Two Column Admin