'Bowling for Columbine' is a documentary by Michael Moore that focuses on violence and its causes in the USA. It's a phenomenal documentary that really makes you think. He's also put a teacher's guide to the film online including great lesson ideas that can be easily adapted to an ESL class. The included materials will give you hours of lesson plan material for intermediate to advanced level courses. Here are some related debate ESL lesson plan links:
First World Obligation
Multinationals