OK now it's clearer for me, you were not talking about Recently Active Threads but about the view of a post + all descendants.

again there are CSS classes you can manipulate there on your own.

Things like <div class="pmsig-174111"> for the message and <tr class="reply-body pmnote-961" bgcolor="ffffff"> for the author.

So you are free to mark each message or author in the way you like.

If someone was providing a JSON list of worst nodes you could even do what you want in JS using a XML_HTTP_request as a nodelet-hack.

There is also an XML interface to read Worst Nodes, but with the downside that you won't necessarily see older worst nodes (like from yesterday)

(I actually use a XML to JSON parser for such a ticker)