Note that i went ahead and added a Rating system.
Currently ratings are 100% private -- i.e. when you rate a thread it doesn't affect anyone else and isn't shown to anyone else; we may change that later.
For now, just think of it as a separate bookmark folder.
When you "Bookmark" a thread, it doesn't get added to your list of rated topics, and vice versa.
Note that the Ignored Topics list will keep a thread from showing up in your list of Recent or Unread topics, but the topic will still show up if you browse a specific forum section.