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.

room34

This plugin is an add-on for Modern Tribe’s The Events Calendar plugin. It adds a “noindex” meta tag to the individual detail pages for events after their end date has passed, to prevent them from appearing in search engines like Google or Bing.
Note that this only takes effect the next time a search engine indexes your site, so past events may still appear in search results for a few days.

noindex Past Events for The Events Calendar

Automatically add a "noindex" meta tag to The Events Calendar's detail pages for past events, to prevent them from appearing in search engines.

Expire Comment Links vs noindex Past Events for The Events Calendar