Shellbot

Posts by Category lets you display a list of posts pulled from a particular category or tag, and optionally 
group them by year, month or first letter of the post title.
Current features include:
<ul>
<li>Set a title to be displayed above list of posts</li>
<li>Shortcode allows post list to be inserted anywhere</li>
<li>Limit how many posts should be displayed</li>
<li>Group posts by year, month or first letter</li>
</ul>
Usage
To display the list of posts, add the following shortcode to your post or page.
Default settings:
<pre><code>[sb_category_posts]
</code></pre>
Custom settings:
<pre><code>[sb_category_posts show="10" cat="3" group_by="year"]
</code></pre>
For full list of parameters see <a href="http://codebyshellbot.com/wordpress-plugins/posts-by-category/" title="Posts by Category" rel="nofollow ugc">the plugin release page</a>

Posts by Category

Display a list of posts from a specific category or tag.

GB071

ecreateinfotech

This plugin automatically converts keywords in a post/product title and category to tags upon saving. It includes a user-editable list of words you want the plugin to ignore
<ul>
<li>Converts keywords in post/product titles to tags</li>
<li>Converts keywords in post/product category to tags</li>
<li>Includes user-editable list of words to be ignored</li>
<li>Setting to enable for title and category separately</li>
<li>Setting to overwrite previous tag and consider only title and category while generating new one</li>
<li>Converts on publish and update.</li>
</ul>
Multi-blog adminstrators take note: this plugin is especially helpful if you’re building a community-based site where tagging is important and your bloggers are not always diligent about tagging.

Auto Tag Creator

Automatically creates tags from post/product title and category, on update or publish.

Posts by Category vs Auto Tag Creator