How about factions with reputation based on completing exam quests (Bayesians? Frequentists? Consequentialists? Bards?), built-in arenas (bets? challenges? predictionbook?), PVP areas where dropping out of arguments without resolving them is punished by karma hits, general chat (permanent open thread?), achievements and meta-achievements ("Karma King: Accumulate 1000 Karma in a Month"?), user profiles (should they show IQ or books read by the players as inventory, as long as they are able to prove that?), random drops ("Downvote Zapper: Negates all downvotes of your next 10 top-level posts and comments."?)