chrisnorthwood

This plugin adds a panel to the Options screen in the admin that allows you to assign an image to a tag.
In order to make use of the image, you must alter your theme to include it where appropriate. In it’s simplest case, this is simply something like <code>echo get_tag_image($tag)</code> or <code><?php foreach (get_the_tags() as $tag) echo get_tag_image($tag); ?></code>, or something.

Tag Images

This plugin adds a panel to the Options screen in the admin that allows you to assign an image to a tag.

jfoucher

This plugin uses the yahoo.com API to find the most relevant keywords from the content of your post, and then adds them as tags.
The tagging is fully automatic, so if you’re using a plugin like feedwordpress to display RSS feeds on your blog as posts, everything will get done as the feed posts are published. No user intervention necessary!

Auto-tags

Automatically add relevant tags to new posts.

Tag Images vs Auto-tags