User checklist plugin for document review?

I’m looking for a plugin that checks users off a list once they’ve commented on a post. Here’s the scenario: I have a members-only blog that’s used for reviewing documents. Each author posts her document, and everyone else is required to comment on it. What I’m looking for is something I can put in a sidebar that will list all the blog’s users and strike through (or style in some other way) each user’s name if she is the entry’s author or has posted a comment.

I can’t find such a plugin, but I thought I’d check with the hivemind before I go off and write it.