It would be nice if I could maintain a list of “favourite” threads for future reference. Of course, I can do that using the bookmarks feature of my browser, but that wont tell me if a thread receives a new post. It’s not the same as “subscribed threads”, besides which, it isn’t possible to add closed (i.e. archived) threads to one’s subscription.
What exactly do you mean by “favorites” thread? I’m a little unsure what you are looking for here.
You can search those Archived Threads and bookmark them: I just tried it:)
Create a special bookmark folder for them;)