Gorakh Shrestha

This plugin allow you to easily fetch popular post and get total view in post. Simply use <code>'orderby'=>'popularity'</code> in query string.
Add <code>'post','posts_per_page'=>-1,'orderby'=>'popularity'); 
$query = new WP_Query($args); 
?></code>
Features
<ol>
<li>Support the custom post type </li>
<li>Option page to allow popular post option in post type.(Setting > MPP Setting)</li>
<li>Can easily get total view for particular post using <code>get_view_number()</code>, <code>get_view_string()</code>. Function must be within loop. </li>
<li>To print the total view for particular post <code>the_view_number()</code> and <code>the_view_string()</code> both function are almost same but <code>the_view_string()</code> return with ‘views’ text.</li>
</ol>

ryokurosu

This plugin is easy to set category ranking. 
If you view the post,Ranking is on the same category.
This plugin:
<ul>
<li>Easy setting ranking widget on same category</li>
<li>Frontpage ranking is able to choose</li>
</ul>
Please contact me if you want additional setting.

Simple Category Ranking

this is a better way to ranking widget with category.

Popular post vs Simple Category Ranking