Very fair, I suppose I should have said human sacreds instead of human nations :P
Although off the top of my head I can't think of too many summonable sacreds for human nations that I'd say are worth taking a hell bless, big issue with hell blessing summons is you are investing so much into something you don't get right away. It's rough spending all your points on something that doesn't help you early game. The fact that most summoned units are hard and expensive to mass in great numbers as well hurts too. Mictland has Ozies, but then again they are an exception to the first point about human sacreds not being worth a hell bless as well :P
I guess some people like doing quite heavy pig blesses for Marverni, I'm not sure it's not a meme, but at least it's some level of popular sometimes :P
If we allow near human nations, specifically with wings, I've seen it done to good effect for Condors with Nazca, although I feel like that's sorta a greedy build on top of a greedy nation. I've also done close to a hell bless with Xibalba... I mean, if your troops are bad enough, no need for money right? (I've lost every game I tried it with soooo.... take it with a grain of salt)
Ah! MA Ermor and LA Lemuria always take hellblesses for their (technically) summoned troops... And they still count as human... right?
Any more sacreds summons worth a hellbless for alone? I can't think of any off the top of my head, but I could easily be forgetting some... Maybe Se'ir (although most of those nations are not doing it for them alone) and I think Jotun Wolfs are sorta close, especially if you can expect a reasonable chance to control mother oak. Do people hellbless Sentinels? I've always sorta gone for a more moderate bless on them, but I could see it.