Most of the resources I have for Model UN are in a huge green three-ring binder. I have been slowly getting those resources in electric form, but am not even close to finished yet. In the meantime, here are some great website resources for reference.

From the UN Association of America:

National High School Model UN:

American Model UN International: (Great Resources for Teaching, Lesson Plans, Strategies, and much more)

Great Strategies for planning and approach: