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.

redwerks

This plugin provides a [columns] shortcode that gives a section of post content multiple columns using css3’s column properties.
The [columns] shortcode requires a closing [/columns] shortcode and accepts the arguments count=”#” to specify the number of columns and gap=”1em” to specify the gap size between columns.
Some examples:
A simple 2 column block of columns. 
 [columns count=”2″]…[/columns]
A 3 column block of columns with a 2em gap in between columns. 
 [columns count=”3″ gap=”2em”]…[/columns]

CSS Columns

Provides a [columns] shortcode that gives a section of post content multiple columns using css3's column properties.

Three Column Screen Layout vs CSS Columns