Okay, this idea came from an other forum I'm on.
Basically it boils down to the ability to be able to ignore all new threads and posts that apppear on a certain (sub)board. The threads and posts placed in that board would then also not pop up in the "Show unread posts since last visit" list. This Ignore boards option would well fit under the "Modify profile" button on your profile. This might make it easier for some folks if they don't want any notifications about, say, the contest boards or the Ask me subboard, for instance.