Mark achievement as a Badge that appears next to the user's icon

It would be great to be able to assign audience members with special badges that appear against their name / icon in comments. We could achieve this my configuring the achievements to say a certain achievement is a "badge". I am aware that it would work best when only one badge is possible, so maybe it would need to be defined as a "role", but I'm open to suggestions. I think it would encourage participation!