I have an add-on which allows my Users to "hide" topics they aren't interested in, and there are topics on my forum I'm not really interested in either. However, as the admin, I'd rather not hide any topic because I do like to see which topics are popular, even if to other Users.
I realize we're talking about eliminating some extra clicks of a mouse, but it would be nice if my Users could make a topic to never show as being Unread, as to say they aren't interested in it.
I think you're best requesting this as an add-on as this sort of functionality wouldn't be something any forum software would offer by default. You can exclude certain nodes from appearing in the 'New Posts' but individual threads is a different thing entirely.