Is there some way to hide all topics within a category from all feeds (recent, popular, new, the digest)? I need the topics to be accessible (and usable) to all users directly, but not searchable or showing up at random.

@julian ok, I was thinking that the nbbpm was here for that! Thank you for your answer!

Yes, I think that makes sense... the adsense plugin (that's what you're using, right?) can be modified and be instructed to look for a specific tag if you don't want ads to be shown on that page... However, it might lead to people abusing that tag so their topics don't show ads... just saying