Every couple months in Children's Church I pick a country for the kids to learn about. We pray for the missionaries from that country that our church supports and write letters to them. I have been teaching the kids how to pray for missionaries.
It is awesome to listen to the kids pray for the missionaries. I wish that the missionaries could hear them pray. There is nothing like the simple faith of a child. I usually have a volunteer each week come up and pray for the missionary. When I forget to do this the kids remind me. If I have the kids pray at other times during class they always pray for the missionary even when I haven't mentioned it. It is neat to see them get excited and involved.