copperblade

Update: If you need more functionality please see the next generation of this plugin at https://wordpress.org/extend/plugins/network-latest-posts/
Creates a widget to show a list of the most recent posts across a WordPress MU installation. It shows the most recent post from each blog. This plugin is based on the work of many authors.
This works on previous versions of WPMU, but not on previous versions of WordPress (where it doesn’t make sense).
<h3>Options</h3>
<ul>
<li>Number of posts to show – list this many posts.</li>
<li>Number of days to limit – only go back this number of days to get posts. Set to -1 for no limit (default).</li>
</ul>

Multisite Recent Posts Widget

Creates a widget to show a list of the most recent posts across a WordPress MU installation.  It shows the most recent post from each blog.

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.

Multisite Recent Posts Widget vs Category Text