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".

Zeno Popovici

Graffino

miguelibero

This plugin adds 1 button to <a href="http://tinymce.moxiecode.com/" rel="nofollow ugc">TinyMCE</a> to clear floating elements. It also adds divs to valid tags so they won’t be deleted if empty.
Originally by <a href="https://wordpress.org/plugins/tinymce-clear-buttons/" rel="ugc">Miguel Ibero</a>.

Clear Floats Button

Adds clear float button to TinyMCE Editor.

Category Reminder vs Clear Floats Button