You will need a plugin. Consider using WP-Stats in conjunction with WP Popular Posts.
You can do it without a plugin if you want. Just some code based on the following to the template where you want the list appearing…
<?php query_posts('category_name=work&showposts=5'); ?>
<ul>
<?php if ( have_posts() ) : while ( have_posts() ) : the_post(); ?>
<li><?php the_title(); ?></li>
<?php endwhile; ?>
</ul>
<?php endif; ?>
that will show the first 5 posts from a category called ‘work’. Not exactly what you asked for in your question, but it’s definitely how to just ‘List Posts in Category X’ 🙂
I did that 2 days ago. You can see it in http://www.europasobreruedas.com/cronicas, at the end the sidebar “IMPORTACIONES AUDI”, “IMPORTACIONES BMW”, etc. I added the code wrotten by monkey at the end the sidebar.php. By
Almost exactly what I am looking for… however I am trying to create a navigation where it displays a list of categories with a sub-list of all posts within each category and loops this.
Something like this:
<li>
<a href="category_url">CATEGORY</a>
<ul>
<li><a href="post_url">POST</a></li>
</ul>
</li>
Of course I would want it to loop until it has listed all categories and all posts within these categories.
Help is greatly appreciated.