My previous post on the virtue of militia training was written before I heard about the atrocity at Virginia Tech. I mentioned in passing that having an armed, ready to act citizenry can help protect against crime. It's not just having weapons available that makes the difference--it's the mindset of "I can make a difference, I should act." That lets someone stop a crime or save lives even without a firearm handy.
Prof. Librescu had that mindset. He saved ten of his students. I've heard that some students blocked the killer from another room, but not their names. If more people had been trained to act in emergencies, rather than wait for the authorities to save them, even more lives might have been saved. That's what militia training can do.
EDIT: One of the students who blocked off the room--and apparently the one who took the initiative--was Zach Petkewicz. He got a couple of other students to help him make a barricade. I suspect there's a lot of power in taking the initiative in that kind of situation. A lot of guys who have no clue what to do will be willing to follow someone else's lead.