Nashita

Simple and clean styling widget for displaying popular posts with thumbnail and post view counter.
After installed the plugin, WP Popular Posts Widget will be in <code>Available Widgets</code> section named <code>Popular Posts</code>.
Optional settings for <code>Title</code> and <code>Number of Posts</code>.

WP Popular Posts Widget

Widget for displaying popular posts with thumbnail and post view counter.

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.

WP Popular Posts Widget vs Simple Category Ranking