Do you keep a simple blog, where you don’t define specific categories for your posts but simply let them all be uncategorized and use tags instead? Do you, like me, feel that all the categorizing stuff comes in the way of your content and your blog? Do you feel that keeping only one category seems superflous, but WordPress just forces you to? Then this plugin might be for you!
This plugin is mostly cosmetic, as it doesn’t change or actually remove any categories, but hides any options to change them, so all posts are in fact put in the default category (usually “Uncategorized”). This currently includes the category section on the edit pages and the “Manage categories” section on the admin pages. Published posts will not mention categories, and the Category widget has been removed.
As it doesn’t actually remove the categories or modify any files, this plugin will not affect any other plugins’ usage of categories. This means “Uncategorized” will show up on statistic pages, etc.

No Categories

Simply disables the usage of categories in your WordPress blog.

darrinb

Build a better category list.
The Advanced Categories Widget is a powerful and flexible category widget for WordPress that makes building and displaying custom category lists a snap.
Organize your site in style with this highly customizable category widget!
Features
<ul>
<li>Build multiple lists!</li>
<li>Select which categories to display.</li>
<li>Choose how to order your categories: name, post count, etc.</li>
<li>Set the order for displaying the categories.</li>
<li>Supports category thumbnails.</li>
<li>Set and preview custom thumbnail sizes, or choose from your site’s registered image sizes.</li>
<li>Show a description of each category.</li>
<li>Set and preview the length of the description.</li>
<li>Select the list format to match your site’s markup. Choose from:<code>ol</code>, <code>ul</code>, or <code>div</code>.</li>
<li>Show post count.</li>
<li>Choose the default (basic) CSS styling or roll your own.</li>
</ul>
Developer Features
This widget was built not only with end-users in mind, but also plugin developers. Almost every aspect of this widget is extensible through filters and action hooks. You can even add your own form fields to the widget form!
<ul>
<li>Need to remove a field from the widget form? Not a problem! Every field is passed through its own filter for easy customization.</li>
<li>Need to modify the output of the widget? Easy! The output is passed through numerous filters, allowing you to customize the post list to meet your project’s requirements.</li>
<li>For a full list of action hooks and filters, please see the plugin documentation: http://darrinb.com/plugins/advanced-categories-widget</li>
</ul>

Advanced Categories Widget

A highly customizable categories widget for WordPress with thumbnails and descriptions.

No Categories vs Advanced Categories Widget