Sorry for double post, but this is completely different topic:
I had an idea of mission kind of slave pen. You would use pickaxe or something to make a hole in the ground without ramps, and then throw bodies of the unconscious there.
1) I think they could not get out, so they would not have to be guarded.
2) Even more importantly, if the pit was only one tile, would the unconscious even get up after first one? What happens in such case?
If they don't, it could be even used to capture large number of, say, spiders (for poison etc), or werewolves, etc.
3) Maybe i am evil, but just imagined largeish pit filled woth awake captives, cheering gals on the embankment, and then one of them throws a firebomb in...