Chances are you already have an idea of what activities you will be doingg or where to get ideas for more, but thought I'd pass on what some of the Youth Leaders are doing - perhaps we could coordinate and do the same activities the same time... even if congregations do it oon their own.
Youth Mission Project: Walk-a-thon
This activity combines with teaching about Mission in a way that children have to do more than just ask for money; they have to earn it by walking 4 km (or whatever).
Youth Mission Project: Chili Lunch
Again, the point is not to have the youth ask for money but to have them do something - take action - to raise funds.