mmfilesi

This plugin shows in the sidebar n post related with the same category(s) of post being viewed. 
The result can be random or chronological order.
Este plugin es un widget que se incluye en el sidebar. Muestra n entradas relacionas con la entrada que se ha cargado. 
Los resultados pueden ordenarse de forma aleatoria o por orden cronologico.
<h3>Donations</h3>
http://www.mmfilesi.com

mmfilesi-random-post

This plugin shows in the sidebar n post related with the same category(s) of post being viewed.

dyersorg

<a href="http://www.dyers.org/blog/better-blogroll-widget-for-wordpress/#changelog" title="Better Blogroll Change log" rel="nofollow ugc">Changelog</a>
The Better Blogroll widget for WordPress allows you to display a configurable number of random links from your WordPress blogroll. This should help to combat link blindness while still letting you to share the link love with more of your favorite blogs.
Some Features:
<ul>
<li>Links can be sorted randomly, by title, or by rating.</li>
<li>The number of links shown is configurable.</li>
<li>Categories from which links are shown is configurable.</li>
<li>Links can be set to “nofollow” if your links are coming from paid sources.</li>
<li>Capable of Displaying XFN Data.</li>
<li>Displays image links, text links, or both.</li>
<li>Links can be in a single list or separated by category.</li>
<li>Can display each link’s category or rating to its right.</li>
<li>The description of each link appears in a tool tip.</li>
<li>Allows you to show an explanation that the list is a rolling blogroll.</li>
</ul>

Better Blogroll

Allows you to display a configurable number of random links from your Wordpress blogroll

mmfilesi-random-post vs Better Blogroll