Nature of Content Rating Plugin?

I’m wondering if anyone knows of a plugin where one could rate their own content via a graphic/text?
I’m looking for a plugin that would be able to place next to the post title a graphic symbol/text identifing that the content is either violent, adult in nature, pg-13, strong language, etc., etc. Also, there would be a key-listing for definitions of the rating symbols. It would be very nice to have this in the create post area where the author could select the icon(s) that would be associated with their post.

Anyone have any ideas or seen this used in WP?
Anyhow, just an idea that I though to throw out there for consideration.
Thanks!