Mark Jaquith

<ol>
<li>Check a category.</li>
<li>Uncheck “Uncategorized”.</li>
<li>Mutter “stupid ‘Uncategorized'” under your breath.</li>
</ol>
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.

Categorized

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

FirstElement

takumin

カテゴリーの選択方法を、従来のチェックボックスからドロップダウンに変えます。 
親子関係を正確に維持しながら、簡単にカテゴリー選択を行えます！
The change to dropdown from checkbox for the category. 
Accurately while maintaining the parent-child relationship, I can do the easy category selection!
<h3>Arbitrary section</h3>
Enjoy it!

Categorized vs Admin DropDown Categories