Roy Tanck

This plugin will help you:
<ol>
<li>Find plugins and themes that are not active on any blog.</li>
<li>Determine the impact in case a theme/plugin needs to be upgraded, removed or reconfigured.</li>
<li>See if a widget is in use on any blogs, and track down where.</li>
<li>Find users who do not have a role on any site (and are not network administrators).</li>
</ol>
This plugin currently does nothing on single-site WordPress installs.

Network Admin Assistant

Helps you manage a WordPress network by displaying useful statistics.

scribu

Ron Rennick

Curtiss Grymala

This plugin adds 2 privacy options in a single install and 3 in a network install. In a network install the network administrators (Super admins) have the option to set the privacy setting for the entire network. When the privacy is set for the entire network, the extra privacy options are not shown on individual site’s Settings -> Privacy.
Features
In a single site WordPress install adds the following privacy options:
<ul>
<li>I would like my site to be visible only to Site subscribers.</li>
<li>I would like my site to be visible only to Site administrators. </li>
</ul>
In a WordPress network activated on an individual site adds the following privacy options:
<ul>
<li>I would like my site to be visible only to Registered network users.</li>
<li>I would like my site to be visible only to Site subscribers.</li>
<li>I would like my site to be visible only to Site administrators. </li>
<li>I would like my site to be visible only to Site contributors (and above)</li>
</ul>
When Network Activated or in the mu-plugins folder in a WordPress network adds the following:
<ul>
<li>A privacy selector in the Network Admin -> Settings page to allow individual site privacy or the 3 above across to network.</li>
</ul>
Support can be obtained through:
<a href="https://wordpress.org/support/plugin/network-privacy" rel="ugc">Try the WordPress Forums first</a>
<a href="http://twitter.com/wpmuguru" rel="nofollow ugc">Twitter</a>
<a href="http://ronandandrea.com/contact/" rel="nofollow ugc">Ron & Andrea</a>
<h3>To Do</h3>
<ul>
<li>Update the robots.txt process to use the constants/functions for wp-content, wp-includes and wp-admin directories (in case those items are in a non-standard location, or the install is in a subdirectory)</li>
</ul>

Network Privacy

Golden oldie that I use on all my staging sites. Although originally developed for Multisite, it works brilliant on standalone sites too, for which I mostly use the plugin.



Every staging site should have this

Adds more privacy options to both single Wordpress sites and WordPress networks.

Network Admin Assistant vs Network Privacy