Plugin Name: Main categories
Plugin URI: http://rudd-o.com/projects/wp-list-main-cats/
Description: Provides a template function to display main categories and a management interface for them
Author: Manuel Amador (Rudd-O)
Author URI: http://rudd-o.com/

##What this plugin does

With this plugin, you can display selected "main" categories on your blog's sidebar or top navigation bar.  Akin to wp_list_cats(), the provided function wp_list_main_cats() accepts the same arguments, but filters out all categories not deemed "main".  You choose main categories via the WordPress category management administration panel.

Another function called wp_list_secondary_cats() allows for the listing of any secondary (non-main) categories in your blog.

Plus, two included widgets let you create sidebar blocks for main and/or categories.

##Why this is useful

It's useful when you want to keep a flat category namespace, or separate topics from site sections.  For example: you select a few categories to be your 'sections' by making them main.  The other categories can be 'topics'.  That way, you can keep an orthogonal separation between sections and topics on your blog.  Thus, the wp_list_main_cats() function comes in handy to generate "main menus" for sidebars or top navigation bars.

More in-depth: hierarchical categories work very well in most settings, but sometimes you want to assign two categories to a post, without having to duplicate a sub-category in another category.  Yes, that sounds confusing.  Here's an example.

Suppose you have a Guides category, which contains two sub-categories: Apache and MySQL.  You also have an Interview category.  What happens when you interview Brian Behlendorf?  Should you select Interview, and then the Apache subcategory from the Guides category?  It doesn't make sense, right?  Should you duplicate Apache in the Interview category?  You can imagine the nightmare on your sidebar, filled with lots and lots of duplicate categories.

##Installation and usage

To use:
- deploy into its own wp-plugins/wp-list-main-cats/ directory (basically, preserve the package's directory structure)
- activate through the plugin manager
- access the Manage panel in the WordPress administrative interface
- go to Categories
- select your main categories
- add the wp_list_main_cats() tag (perhaps in replacement to the wp_list_cats()) on your template

##License

As always, it's GPL, dude.