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.

yanniks

This is the Shariff for WordPress plugin based on c’t Shariff.
For more information, check out the original <a href="https://github.com/heiseonline/shariff" rel="nofollow ugc">GitHub project</a> and the <a href="http://ct.de/shariff" rel="nofollow ugc">c’t information page</a>.
<blockquote>
Shariff enables website users to share their favorite content without compromising their privacy.
Facebook, Google+ and Twitter supply official sharing code snippets which quietly siphon personal data from all page visitors. Shariff enables visitors to see how popular your page is on Facebook and share your content with others without needless data leaks.
Shariff <code>(/ˈʃɛɹɪf/)</code> is an open-source, low-maintenance, high-privacy solution maintained by German computer magazine c’t and heise online.
</blockquote>
Shariff supports sharing buttons for Facebook, Twitter, Google+, LinkedIn, Pinterest, Reddit, StumbleUpon, XING, WhatsApp and mail. 
Select which color you want, set the button location, select the orientation fitting most to your website and set the TTL just as you want.

Shariff for WordPress

Shariff enables website users to share their favorite content without compromising their privacy.

Network Admin Assistant vs Shariff for WordPress