Display a list of 15 posts selected randomly by using the MySQL RAND() function for the orderby parameter value:
 <ul><li><h2>A random selection of kingphp posts</h2>
   <ul>
 <?php
 $rand_posts = get_posts(‘numberposts=15&orderby=rand’);
 foreach( $rand_posts as $post ) :
 ?>
   <li><a href=”<?php the_permalink(); ?>”><?php the_title(); ?></a></li>
 <?php endforeach; ?>
   </ul>
 </li></ul>
 more: http://codex.wordpress.org/Template_Tags/get_posts#Random_posts