Mark Jaquith

<ol>
<li>Check a category.</li>
<li>Uncheck “Uncategorized”.</li>
<li>Mutter “stupid ‘Uncategorized'” under your breath.</li>
</ol>
<p>Sound familiar? With this stupidly simple plugin, you just have to do the first step. When you check a category and the default category was the only thing checked before you clicked, it’ll uncheck the default category for you. Boom.</p>


Categorized

Unchecks the default post category when you first select a non-default category

Masahiro NAKASHIMA

twinpictures

katanyan

rinoshiyo

nashiko

<p>Installing this plugin allows you to adjust the behavior of the area below the posts screen category and custom taxonomy box.</p>
<ol>
<li>Stop the checkbox from moving</li>
<li>Change checkbox to radio button</li>
<li>Make parent categories unselectable</li>
<li>Required to Category or Taxonomies</li>
</ol>


Adjust Admin Categories

Installing this plugin allows you to adjust the behavior of the area below the posts screen category and custom taxonomy box.

Categorized vs Adjust Admin Categories