Is there a plugin to hide contributor names from posts and feeds?

I’m running a blog where we wish some posts to be published anonymously, whereas other posts display the name of their author.

So far, I have simply removed all references to authors in theme templates and feeds. But I’d rather have it as an option, whether or not to disclose author names, either post by post (show the author’s name for post A but not for post B) or author by author (show author X’s name, but not author Y’s), but preferably both.

Is there some plugin that would allow me to do something like this?