It's named "Terror In The Name Of God: Why Religious Militants Kill" by Jessica Stern. Now that I look at the title again I guess it focuses on religiously motivated terrorism. Most of it is crazy Muslims of fundamentlist Jews but some of it is Christian fundamentalists in the US that do things like kill abortion doctors.
I subscribe to Scribd on my Ipad, which is an all you can read book service for $8-9 per month, which is good but not as good as it sounds because they don't have most new books. I was just exploring to decide what to read next and I stumbled on the above book and it looked good, so I'm reading it. And it is pretty good. By the references though I think it's maybe 5-10 years old. That said, I doubt terrorist psychology is changing that quickly so I think the contents are still valid today.