If what matters to you is the forum, generally speaking, what you need is a better offtopic subforum, with plenty discussions over a wide variety of topics. This needs time, and the only thing you can do to improve it is advertising it in the social networks and of course, very active administrators to promote events and activities and control the posts.
You can also add a roleplaying forum, that is indeed interesting to player community.
And if you are interested in improving the wow-concerning subforums, well, you need to think whats what matters to every player, proud of his/her respective class and well-being inside the game? Passively: Wealth, appearance (transmog), achievements and collectibles (mounts, pets AND Battle Pets) ; and actively: DPS/ HPS/ TPS, PvP and BGs, how to improve their class to the limit, macros, consumibles, professions, etc... Maybe a pinned topic about soloing old content in each class subforum, since now its fairly easy to enter old raids.
Just take a look at some important forums(elitist jerks, MMO, even Blizzard's xD), you'll get plenty ideas, but the most important thing is to advertise in every way you can imagine, and having dedicated people to each subforum
Good luck IV, we love you
Edited by Araielle, 01 December 2012 - 05:44 AM.