I'm really keen on getting involved with the International Committee of the Red Cross, because: 1. It's the preeminent authority on international humanitarian law; 2. it's an organization of immense integrity (even if it's quite conservative, intellectually); 3. it's in Geneva.
Whole poking around on their website, I noticed that there is a hilarious lack of diversity as far as the membership of some of its organs goes. Check out the names, here -- it reads like something from the French Revolution:
Assembly Council
Mr Jakob Kellenberger, President
Mr Jacques Forster, permanent Vice-President
Mr Jean Abt, member of the Committee
Mr Jean de Courten, member of the Committee
Mr Jacques Moreillon, member of the Committee