Sacrificing is really cheap. It's like the gods are trash cans or something.

How about something a bit more noticable?

For example, XXX sacrifices YYY to the dark/grey/light gods, and it vanishes in a greasy cloud of smoke/fades into the ground/vanishes in a flash of light. Or, if revealing alignment is bad, maybe let the player configure sacrifice appearance from a small menu of choices. Or, modify the sacrifice command so you can sacrifice to someone.

It might get really interesting if there were factors, perhaps depending on who you sacrificed to and what you've been up to, that could affect the success of sacrificing. "Drokalanatym doesn't appear to hear you." Maybe always accept corpses, or maybe even there... "You sacrifice the corpse of the paladin to Shokai. You feel Shokai's gaze upon you." (Ok, yeah, requires the imms set out and mark mobs/races/classes/aligns as significant to them, maybe that's too much work).

How about giving it a bit of lag?

Doesn't need to be a lot, just enough to make sacrificing a bit more of a concious decision -- to give it slightly more of a ritual flavor as opposed to the blatantly obvious combat tactic it currently is for when your hands are full.

If you're not already doing it, how about giving morale a bit of a boost when you sacrifice something powerful? Or even just an occasional booming "well done" from the intervening diety?