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".

tomasbulva

Allows to edit categories in bulk at attachement/media page, needs to have categories for media enabled.

Bulk Categories Edit for Media

Allows to edit categories in bulk at attachement/media page, needs to have categories for media enabled.

Category Reminder vs Bulk Categories Edit for Media