Aaron Butacov

This simple plugin allows you to use the tab-key inside the post editor to indent code or paragraphs.
This plugin should work with all versions of WordPress, but has not been tested in versions earlier than 2.9
<ul>
<li>Allows for both multi-line and single line indenting</li>
<li>Works in all major browsers.</li>
<li>Toggle-able on each post. Enable or disable tabs automatically without reloading the page.</li>
<li>Only works in the HTML editor</li>
</ul>

Tabs in Post Editor

Write code in the WP post editor? Hate not being able to use [tab]s? Now you can.

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.

Tabs in Post Editor vs Three Column Screen Layout