isikom

Category Text add a widget that allow to add arbitrary text or HTML code, different for each category of your blog. 
It’s very usefull for SEO, because you can make different text for different category, so also different banner etc. 
Now you can select also the home page position.
The plugin born from idea of <a href="http://www.rossozingone.it" title="web agency" rel="nofollow ugc">Vanny Rosso</a> for his blog <a href="http://www.fantagiochi.it" title="on line games" rel="nofollow ugc">Fantagiochi</a>

Category Text

category text allows you easily to add a widget for a Category Text-Box.

kousuke.kikuchi

This plugin provides to append one category to all blogs for wordpress mu administrator. But this plugin is still testing.
<h3>To Do</h3>
nothin.

common_category

This plugin provides to append one category to all blogs for wordpress mu administrator.

Category Text vs common_category