As far as I know, (and I've played for a few months now), there isn't any sort of structure for gangs. The gang I'm in uses an external blog for everything. Perhaps a new, structured gang feature would be a good addition to the game?  You could have it so a person founds a gang, and can select for there to co-leaders, for for him to be the only leader. Once founded, you can send invites for people to join the gang, or they can apply. Anyhow, I'll outline some of my thoughts for this below.

-1 or more leaders.

-Invitation for people to join, plus an application button on the gangs page.

-A small internal, gang-only forum.

-A bulletin board, for the gang leaders to post the latest important info.

-A gang page for those who are not in the gang to look at, for information of joining and whatnot.

-Multiple, nameable ranks in the gang.

-Selectable rank-privledges, where say, the lowest rank can't view a certain folder in the forums, or another rank has moderator privledges in the internal forum., ect.

Just an idea, I'm sure it's been mentioned before.