Ady Romantika

This simple plugin is a widget that displays a list of random posts on your widgetized sidebar.
It supports multiple instances with WordPress 2.8 and above.
<h3>Configuration</h3>
<ul>
<li>Widget title: the title of the widget</li>
<li>List types: ul for bulleted list, p for paragraph, br for paragraph with line breaks</li>
<li>Post count: Number of random posts you would like to be displayed</li>
<li>Category: Only this category will be selected as the source</li>
</ul>

Random Posts Widget

This simple plugin is a widget that displays a list of random posts on your widgetized sidebar. It supports multiple instances with WordPress 2.

Scribit

With Random plugin you can insert into your WordPress website one or more random contents coming from your posts. 
The source contents can be pages, posts or custom post types. 
You can display information in many different ways: 
* A list of post titles 
* One or more full contents or excerpts 
* Raw URLs to posts permalink

Random

This plugin give to your website the possibility to get random content for specific posts types. You can use to give to your visitors random posts, or random woocommerce products for your clients.
Very useful in my opinion.

Wikipedia style!

Random, a great plugin designed to insert random contents, posts and other types, into your website. Enjoy its shortcodes!

Random Posts Widget vs Random