Aaron D. Campbell

Expire Comment Links was inspired by <a href="http://yoast.com" rel="nofollow ugc">Joost de Valk</a> 
in an article he wrote called 
<a href="http://www.searchcowboys.com/columns/764" rel="nofollow ugc">Comment links: an experiment</a>. 
It all started when Matt Cutts talked about how Google changed how it handles no 
follow links in his article on 
<a href="http://www.mattcutts.com/blog/pagerank-sculpting/" rel="nofollow ugc">PageRank Sculpting</a>.
No one knows for sure yet if this will be beneficial or not, but for those that 
want to be on the cutting edge and try this experiment for themselves, this 
plugin automates everything.
Requires PHP5.
You may also be interested in <a href="http://wpinformer.com" rel="nofollow ugc">WordPress tips and tricks at WordPress Informer</a> or general <a href="http://webdevnews.net" rel="nofollow ugc">Web Developer News</a>

Expire Comment Links

Allows you to stop displaying links for old comments. PHP 5+ required.

unforgivenhobbies

Multisite search visibility indicator is a lightweight plugin that keeps you informed at a glance whether your site — or any site in your network — is accidentally blocking search engines.
WordPress has a built-in setting under Settings → Reading called “Search Engine Visibility”. When enabled, it adds a <code>noindex</code> directive that tells search engines not to index your site. This is easy to accidentally leave on after development, and notoriously hard to notice.
This plugin adds a persistent indicator to the WordPress toolbar so you never miss it again.
<h4>Features</h4>
<ul>
<li>Toolbar indicator visible to administrators at all times (front-end and back-end)</li>
<li>Color-coded status: green when search engines are allowed, yellow/red when blocked</li>
<li>Multisite ready: shows a per-site breakdown across your entire network</li>
<li>Each site in the dropdown links directly to its Reading Settings for a one-click fix</li>
<li>Bulk management page (Multisite only): allow or discourage search engines across all — or selected — sites in a single action</li>
<li>Zero configuration required — install and it just works</li>
<li>No external dependencies, no tracking, no bloat</li>
</ul>
<h4>Multisite Bulk Management</h4>
On a Multisite installation the plugin adds a Search Engine Visibility page under Network Admin → Settings. From there you can:
<ol>
<li>See every site in the network and its current visibility status</li>
<li>Select individual sites or all sites at once</li>
<li>Apply “Allow search engines” or “Discourage search engines” in one click</li>
</ol>
<h4>Who is this for?</h4>
<ul>
<li>Agencies managing WordPress Multisite networks</li>
<li>Developers who frequently spin up and hand off sites</li>
<li>Site owners who want a quick sanity check without digging through settings</li>
</ul>

Multisite search visibility indicator

Adds a toolbar indicator showing which sites discourage search engines. Supports WordPress Multisite with bulk management.

Expire Comment Links vs Multisite search visibility indicator