wondermill

<p>If you want to graphically display a random list of your posts with their featured image in the side bar, then this is the plugin for you. This plugin allows you to set the category IDs (or all categories) you want to pull the random posts from, the number of random posts to display, the maximum width and height of the featured image thumbnail, the widget title, and the colors of the surrounding box.</p>


Random Posts with Thumbnails

Puts a list of clickable random posts with their featured image in your sidebar as a widget, this list is customizable.

Jeremy Green

<p>This plugin allows you to display random content anywhere on your site using a shortcode or widget. You can group your random content together, allowing you to display different content in multiple locations throughout your site.</p>
<p>The content is added via a custom post type, so you have full access to the tinyMCE editor. This allows you to easily add images, text, and links to your random content.</p>
<h4>Using a widget</h4>
<ol>
<li>Navigate to Appearance->Widgets and add the Random Content widget to a sidebar.</li>
<li>Select a group from the dropdown. If you don’t create a group, the widget will use all entries.</li>
</ol>
<h4>Using a shortcode</h4>
<p>Place the shortcode <code>[random_content]</code> anywhere on a post or page.</p>
<p>To choose entries from a specific group, add the <code>group_id</code> parameter. For example, <code>[random_content group_id="64"]</code>.</p>
<p>To specify the number of posts to show, add the <code>num_posts</code> parameter. For example, <code>[random_content group_id="13" num_posts="3"]</code>.</p>


Random Content

Randomly display any content anywhere on your site.

Random Posts with Thumbnails vs Random Content