robpannell

From the plugin admin screen you can create rules by specifying a key word or phrase along with an existing 
WordPress category. Th plugin then scans post titles for the key, and adds the specified categories as appropriate. 
By default the plugin will automatically check newly created posts when a page is loaded, however this can be set to manual via a button in the admin screen.
I can’t guarantee any support, but if you use the support forum I will do my best to help you with any issues. 
Feel free to suggest improvements too.

Smart Categories

This simple plugin adds categories to posts based on key words or phrases in the title.

turtlepod

<a href="http://genbu.me/plugins/fx-categories-widget/" rel="nofollow ugc">f(x) Categories Widget</a> will register a custom widget “Categories +” it’s just like WordPress default Categories Widget, but with taxonomy option just like in Tag Cloud widget.
Features:
<ol>
<li>Simple and easy to use.</li>
<li>Works flawlessly for multiple widget instances.</li>
<li>Select all build in taxonomy (such as category and tag) and all custom taxonomy.</li>
<li>Now you can display your Post Tags as list or drop down (not only as tag cloud).</li>
<li>The GPL v2.0 or later license. 🙂 Use it to make something cool.</li>
<li>Support available at <a href="https://genbu.me/contact-us/" rel="nofollow ugc">Genbu Media</a>. 
Notes for developer: </li>
</ol>
<h4>Github</h4>
Development of this plugin is hosted at <a href="https://github.com/turtlepod/fx-categories-widget" rel="nofollow ugc">GitHub</a>. Pull request and bug reports are welcome.

Smart Categories vs f(x) Categories Widget