There's been discussion about instant death poisons and the Neutralize Poison spell, which gave me some ideas. Only a few of these ideas are likely to be incorporated into Liber Zero; most of them are more like potential house rules.
The parts that make it in have only a little to do with poison, but more to do with Raise Dead, which I was examining in connection with death by poison. The popular opinion seems to be that a character that dies by poison can't be raised from the dead unless the poison is removed. Thus, you need to cast Neutralize Poison first, then Raise Dead before that spell expires. I think this line of thinking came in via AD&D, but I haven't looked in the 1e books to see if this is an actual AD&D rule or not.
It's not mentioned in the LBBs, and I think it's more appropriate to let Raise Dead raise the dead, regardless of cause of death. There's no rule that wounds have to be sewn closed before raising the corpse of someone killed by a sword, so why should you have to neutralize poison in a corpse killed by poison (unless you're planning to eat the corpse...) Maybe I'd add the restriction that only the body parts present may be raised; a severed head can be re-attached if in contact with the rest of the body, but a new head won't grow in place of a missing one.
Another thing about Raise Dead that will make it into Liber Zero is a rule that I actually objected to previously: requiring an adversity (system shock) roll before a corpse can be successfully raised. Failure means the corpse is too badly damaged to be restored. It's actually hinted at in the LBB description of the spell: "Naturally, if the character's Constitution was weak, the spell will not bring him back to life." In contrast, losing a point of Constitution is not mentioned, and I think the Con-based adversity roll is a reasonable substitute. It also covers the death by poison situation; if a poisoned character fails the adversity roll, the character can't be raised because too much poison is lingering in the body. In that case, Neutralize Poison may allow a second Raise Dead attempt. Again, the character must make an adversity roll. In general, a failed adversity roll means that character can never be raised unless the situation changes: lost body parts are restored magically, or wounds are sewn closed, for example.
The house rule for instant death poisons that occurred to me was allowing poisoned characters to be in a coma and about to die, instead of actually dead, if an adversity roll is successful. The number of rounds of coma equals the victim's hit dice. Neutralize Poison will work on a comatose victim, but not on a dead victim, except to allow that second chance already mentioned.
Another house rule that occurred to me is how to quickly determine poison delay times, without needing to look up every single one. Since in general special abilities become more likely and more deadly as hit dice increase, I figure a simple one hour delay for 1 HD venomous creatures, minus 1 turn per HD. At 7 HD, the delay should be 0 turns, but I would change that to 1 round, reserving instant death poisons for creatures of 13+ HD, which makes the purple worm's poison very nasty.