Not what you're probably thinking of. I just had this thought about a set of weekly quests that require certain races and/or genders to be in your party (4-man, 8-man groups, if not 2). It would bolster interactivity with others, provided the rewards were well-due (increased gil, tomes, rare items?)

One in particular, involving the Monk temple and the Fist of Ralghr, called "U Mad Bro?" Where at the final boss, if you had a male Hyur Highlander in the group (which would be necessary to do the quest) said character would become confused during the boss battle, so you'd have to deal with one of your own members coming after you while dealing with the boss/AoE/etc. Maybe even throw in some non-fighting mechanics where you have to activate and control a certain machine in order to weaken the boss but have to keep the confused member from attacking the person utilizing said mechanic in order to do so?

Just a thought. Maybe you guys have other ideas you'd like to chime in with?