Well, I haven't done anything too evil, I think. I just ... don't care anymore about those nameless immigrants. Loss of 1 notable dwarf (like one of the starting seven, who became a countess, or a good crafter) is a bad thing. Loosing 15 recruits to a siege is just a lot of cleanup. I also chain dogs to the entrance to slow down goblins. After another siege I decided to dig out a necropolis, and build a lot of coffins set to burial. This should take care of the problem. I'll also drop my civilian defense program with everyone having a wooden crossbow, but not enough bolts, and no good skills. Professional army and a danger room will be the way to go from now on. Oh, and lots of weapon traps. In my case it is rather incompetence and general not caring than cruelty that kills my dwarfs.
Come to think of it, I'll have to do something with those damn goblins and trolls in cages.
Oh, I just remembered, I'm using the "automated cat rover" method to scout the caverns. I ordered 2 screens of animals to be dumped into caverns from 1 z-level drop, including 2 litters of kittens. I didn't stop when some FB entered the caverns, but considered it a good thing, since it will scare away those animals, and help them scout for me. Well, it works to some degree, but a lot of these animals died. At least they are not my dwarfs, and it was probably worth it.
I also don't care much, when some patients die of starvation / dehydration. It keeps the beds free. At least I don't murder them on purpose.