Abbas S

This plugin gives you an URL on which random posts from all your posts are shown.

displayrandompost

This plugin gives you an URL on which random posts from all your posts are shown.

CrestaProject

FREE Crest Posts Widget is a simple but powerful WordPress Widget which displays your posts with thumbnail and many other options like the ability to show the date, the number of comments, to change the length of the excerpt, change the size of thumbnails and much more.
Some features:
<ul>
<li>Easy to use interface</li>
<li>Change post title heading tag</li>
<li>Display the date</li>
<li>Display the comments count</li>
<li>Choose thumbnail size</li>
<li>Choose excerpt lenght</li>
<li>Order posts by date, title, comment count and random</li>
<li>Filter posts by category</li>
</ul>

Plugin Homepage 
http://crestaproject.com/downloads/cresta-post-widget/

Cresta Post Widget FREE

Widget for show all posts or filter by category. Many options available including show thumbnail, excerpt, date and comments count.

displayrandompost vs Cresta Post Widget FREE