The best resource I can currently recommend on this topic is "Jesus the Pacifist" by Matthew Fleischer. The book will be released early next year. It is a fantastic look that digs into Jesus, his actions, his specific teachings, and the implications of all that he did. The book is particularly helpful for the brand of Christians who love to have verse wars and proof-text everything. Since the Bible doesn't specifically lay out all versions of pacifism (though it leans more that way than the way of allowing violence), proof-texting Christians think they can ignore a call to non-violence. Fleischer does a fantastic job of showing us how nonviolence pervades the teaching and revelation of Christ and digs under the surface of the numerous, explicit teachings and actions.