There should be villages like this  http://www.hulu.com/watch/115823/legend-of-the-seeker-fury

A band of people descended from the zealous warriors of an ancient bloodthirsty and criminal wizard. Perhaps there could be some repercussions from donning them as your new "homicidal" entourage instead of breaking their chains of bondage.

Maybe it could have something to do with not being able to take prisoners, decreased prestige, occasionally losing control of your Sovereign due to rage, or diplomacy/recruiting penalties. On the up-side, your opponent's morale is lowered, and you have some murderously strong warriors ... however perhaps the rest of your army's will receive a reduced morale. Maybe your new homicidal friends will randomly kill a visiting diplomat, or a disgruntled family member. Also, maybe these people will flip sides (join the other guy) if your opponent is more murderous or more awe inspiring than you (Dragon being case-in-point for the latter option, while Evil and Cruel Fallen emperor could be case-in-point for the first).

Edit: also, if Sacrificial Temples (Death Worshiping) could allow limited Necromantic spells (even without a spell of Necromancy) ... then that would be totally awesome. Also, if they increase Zombie Caps and SKeleton caps for magically created (or summoned) undead hoards, that would be cool as well.