I fail to see in history examples of terrible means achieving good ends. I know people (usually bad people) claim that the solution for a real problem is taxation, war or genocide, but when they implement their atrocities the result is just as bad as the means.
I can understand that it is possible that undesired means can lead to desired results, as when cutting someone's throat is the way to save his life making him breath again. I'm just saying that history (specially political history) is not full of examples like this.

I'd like to remember that the Non Aggression Principle (NAP) does not need to be the bedrock over which the whole morality rests in other to be useful. I see the NAP as a way of concentrating a huge philosophy of liberty and peace in a simple and easy sentence. Sure, it is not the ultimate perfect solution, but it is a very strong tool for us to use to understand the world. For instance, strikes can be classified as peaceful when the strikers do not attack those who show up to work, and not peaceful when they do. Nowadays people are used to think about strikes as a workers right, including aggression, but NAP helps us see that the violence used may render the whole movement immoral.