Just add a [DISCONTINUED], [ON HIATUS] or something after the title. It would give the forumites and visitors a better idea of what is going on.
If some campaign has finished because the adventure was completed or a TPK happened

Come to think of it, putting [FULL] or [RECRUITING - N SLOTS] or [RECRUITING - PC TAKEOVER], etc after the titles of ongoing campaigns could be useful to.
What say ye?