Tag Plugin to Add Description field to tag

I have tried searching for this, but have not been able to find any sort of plugin that would add a field to the tags management allowing the addition of a description, similar to what is allowed with Categories.

If anyone knows of one, could you point me in the right direction.

I know the line between tags and categories gets blurred in my mind, but we have a large number of topics that may be associated with each post which we use tags for. When they click on the tag, I would like to design the tag archive page to display the description information above the list of posts with that tag.

If there is no plug in that will associate a description field with each tag that can be referrenced in the template, does anyone have any work around ideas?

Thanks