I've used the resources at Meetup.com to create an international community for NationStates players. Note that signing up doesn't commit you to anything. I've created a single arbitrary meeting date for NationStates 10th Anniversary, which you can use, change, or ignore.
Please sign up whether you plan to attend or not. If they start to spam you or something (and I don't think they will - I know I won't) you can always drop out. At this point I'd like to see people sign in just to get a better feel for the demographics of folks interested in possible meetings. If the signup density is sufficient in New York or London or Bonn or Melbourne, by all means, set up a meeting. If enough people sign up, we might find some nice regional nodes developing for people to travel to in November.
Have a look!
Edit: Go into your settings and disable all the email notifications you don't want to get. Apparently I was wrong about the potential for spam.