Four Nodes

Simple plugin to display random posts on your wordpress blog. Plugin provides a widget to display random posts in sidebar. 
Also comes with a shortcode [randomposts] to include on pages.
<ul>
<li>Easy to install</li>
<li>Picks Random Posts</li>
<li>Ability to select from specific category</li>
<li>Limit number of posts</li>
<li>Shortcode support</li>
</ul>

FourNodes Random Post

Displays Random wordpress posts in a sidebar widget. Also, provides shortcode to display random posts on pages.

RobMarsh

Random Posts displays a list of randomly chosen posts. The output can be customised in <a href="http://rmarsh.com/plugins/post-options/" rel="nofollow ugc">many</a> ways.
This plugin requires the latest version of the Post-Plugin Library: <a href="https://downloads.wordpress.org/plugin/post-plugin-library.zip" rel="nofollow ugc">download it now</a>.
<h3>Version History</h3>
<ul>
<li>2.6.2.0
<ul>
<li>new {imagealt} output tag — rather like {imagesrc}</li>
<li>{excerpt} can now trim to whole sentences</li>
<li>content filter can now take parameter string</li>
<li>widget can now take parameter string</li>
<li>output can be appended to posts & feeds</li>
</ul>
</li>
<li>2.6.1.0
<ul>
<li>the current post can be marked manually</li>
<li>widgets now honour the option to show no output if list is empty</li>
</ul>
</li>
<li>2.6.0.1
<ul>
<li>bug fix: installation code was failing on some systems</li>
</ul>
</li>
<li>2.6.0.0
<ul>
<li>version bump to indicate compatibility with WP 2.6</li>
<li>fix to really include attachments</li>
<li>new parameter for {imagesrc} to append a suffix to the image name, e.g. to get the thumbnail for attachments</li>
</ul>
</li>
<li>2.5.0.11
<ul>
<li>new option to include attachments</li>
<li>{php} tag now accepts nested tags</li>
<li>new output tag {authorurl} — permalink to archive of author’s posts</li>
</ul>
</li>
<li>2.5.0.10
<ul>
<li>fix for page selection in old versions of WP</li>
<li>made omit current post try harder to find current post ID</li>
</ul>
</li>
<li>2.5.0.9
<ul>
<li>new option to match the current post’s author</li>
<li>extended options for snippet and excerpt output tags</li>
</ul>
</li>
<li>2.5.0.7
<ul>
<li>new option to show by status, i.e., published/private/draft/future</li>
<li>{categorynames} and {categorylinks} apply ‘single_cat_name’ filter</li>
<li>fixes bug in WP pre-2.2 causing installation to fail</li>
</ul>
</li>
<li>2.5.0
<ul>
<li>{image} has new post, link, and default parameters</li>
<li>new {imagesrc} tag</li>
<li>fix to empty category bug</li>
<li>excluded posts bug fix</li>
<li>fix for intermittent bug with ‘omit current post’ option</li>
</ul>
</li>
<li>2.5b26
<ul>
<li>reverted thumbnail serving (speed)</li>
<li>fix current post after extra query</li>
</ul>
</li>
<li>2.5b25
<ul>
<li>option to sort output, group templates</li>
<li>removed ‘trim_before’ option added more logical ‘divider’</li>
<li>{date:raw}, {commentdate:raw}, etc.</li>
<li>fix for {image} resizing when and not </li>
<li>{image} now serves real thumbnails</li>
</ul>
</li>
<li>2.5b24
<ul>
<li>fix for recursive replacement by content filter</li>
<li>fix to {gravatar} to allow for ‘identicon’ etc.</li>
<li>fix to {commenter} to allow trimming</li>
<li>fix a warning in safe mode</li>
</ul>
</li>
<li>2.5b23
<ul>
<li>new option to filter on custom fields</li>
<li>nested braces in {if}; condition now taggable</li>
<li>improved bug report feature</li>
<li>better way to omit user comments</li>
</ul>
</li>
<li>2.5b22
<ul>
<li>fixes for tag bugs</li>
<li>show_pages option can now show only pages</li>
</ul>
</li>
<li>2.5b19
<ul>
<li>fix for content replacement filter</li>
</ul>
</li>
<li>2.5b18
<ul>
<li>fix output filter bug</li>
<li>new conditional tag {if:condition:yes:no}</li>
</ul>
</li>
<li>2.5b16
<ul>
<li>fix for {php}</li>
</ul>
</li>
<li>2.5b15
<ul>
<li>fix bugs, add ‘included posts’ setting</li>
</ul>
</li>
<li>2.5b14
<ul>
<li>fix file-encoding, installation error, etc.</li>
</ul>
</li>
<li>2.5b11
<ul>
<li>some widget fixes</li>
</ul>
</li>
<li>
2.5b9
<ul>
<li>clarifying installation instructions</li>
</ul>
</li>
<li>
<a href="http://rmarsh.com/plugins/random-posts/" rel="nofollow ugc">previous versions</a>
</li>
</ul>

FourNodes Random Post vs Random Posts