robfelty

Category reminder uses javascript to assert that a category has been assigned 
to a post before publishing it. If no category is assigned, then it will 
prompt the user to assign before publishing.

Category Reminder

This plugin requires users to assign a category to each post other than "Uncategorized".

Ben Huson

<blockquote>
This plugin in only required for versions prior to WordPress 3.5 
 I am no longer continuing to provide support for this plugin. If anyone would like to take over commit access please contact me via the details in my profile.
</blockquote>
This plugin collapses and reduces the height of hierarchical category and taxonomy panels in the WordPress admin.
It always bugged me that when editing a post the categories panel took up so much height if you only had a few categories. This was also the same for custom hierarchical taxonomies.
This plugin just adds a couple of styles to your admin to override this and collapse that space.
I created an initial patch for this which, with contributions from other WordPress developers, was included in WordPress 3.5. You can <a href="https://core.trac.wordpress.org/ticket/15925" rel="nofollow ugc">see the patch here…</a>

Compact Taxonomy Checkboxes

Collapse and reduce the height of hierarchical category and taxonomy panels in the WordPress admin (not needed for WordPress 3.5+).

Category Reminder vs Compact Taxonomy Checkboxes