I love all of the Zinn Education Project lessons that I have used in the classroom. They are a hit every time. Students have been able to connect with the subject matter at a deeper level and make connections to their current lives.
But my favorites are the Teaching the Vietnam War: Beyond the Headlines lessons. These are rich and thought-provoking. The best part of teaching them, for me, is at the end when students are challenged to think about how they too can advocate for social justice and add their voice to a cause worth fighting.