Richard Vencu

This plugin creates and maintains one or multiple hierarchies of blogs in the WPMS network. Options screens appear in network admin dashboard. The blogs hierarchy can be used for several purposes such as:
<ol>
<li>consolidate posts (or latest posts) from descendant blogs only</li>
<li>display a list of descendant blogs or even a tree of blogs from any node</li>
</ol>
Other features
<ol>
<li>Hierarchy cannot loop (cannot set as parent one of the descendants or itself)</li>
<li>The main site (blog_id 1) cannot have a parent</li>
<li>Individual blogs may be taken out of hierarchy</li>
<li>Multiple independent hierarchies may be created 
Limitations: this plugin is not optimized for large installations. More than 50 blogs can be hard to manage.</li>
</ol>

Network Sites Hierarchy

This plugin creates and maintains one or multiple hierarchies of blogs in the WPMS network.

webvitaly

<ul>
<li><a href="http://web-profile.net/wordpress/plugins/taxonomy-checklist-tree/" title="Taxonomy Checklist Tree" rel="nofollow ugc">Taxonomy Checklist Tree</a></li>
<li><a href="http://web-profile.net/donate/" title="Donate" rel="nofollow ugc">Donate</a></li>
<li><a href="http://web-profile.net/wordpress/plugins/" title="WordPress plugins" rel="nofollow ugc">WordPress plugins</a></li>
</ul>

Taxonomy Checklist Tree

Plugin sets Category/Taxonomy checklist hierarchical tree-view by default.

Network Sites Hierarchy vs Taxonomy Checklist Tree