Featured Images for Categories will add WordPress Featured Images to both categories & tags. You can easily assign an image to each category or tag and then display a gallery style block of images via a widget or shortcode.

Check out the video here for a quick summary on how the plugin works.

(NB. Two Pro features are also shown in this video: custom taxonomies and support of registered image sizes).

The plugin has a comprehensive documentation page located here: http://helpforwp.com/plugins/featured-images-for-categories/

Work with custom taxonomies?

We also have released a Pro version that supports the following:

• Custom taxonomies
• Additional widget to featured individual terms in a widget area
• Support for all registered image sizes in your WordPress theme
• A PHP function call for developers to access the featured images assigned to a category
• Ability in the shortcodes to specify exactly which categories to display by category ID

More info on the Pro version available here

http://helpforwp.com/downloads/featured-images-for-categories/