I've got a few suggestions for the clan system, I've forgotten all of them except one, and when I remember the rest I'll add them to this post.

Founder rank
Abilities:
The creator of the clan with absolute power
a separate rank from leader
the ability to demote leaders and promote new ones

Reason:
It's a bit annoying to have to go to a clan moderator when you'd like to remove a leader for any reason.