Alright, so amid some mild brainstorming I have a thought.
First off, I'm considering yet another hostile civ, based in part on the warlocks from 34.11 Masterwork. Essentially mad druids who can raise the dead through a corrupted form of magic they normally use to flashgrow saplings and such or something of that nature. This could make attacks by these renegade nature worshippers being especially dangerous since while they wield wooden arms and armor, they also have the potential to raise any and all as undead warriors to fight for them.
Second, I'm considering replacing Jungle Beasts with "Quagmire Zombie" creatures, victims of the mad druids wandering the swamplands of the world, with castes to reflect dwarves, elves, humans, kobolds, and goblins with the same buildingsmasher tendencies of the roaming horde Beasts and possibly rounded up to fight by goblins and the mad druids themselves.
Third, some kind of shiny new workshop in magma and unpowered varieties to produce some kind of new alloy or two that's somewhat resource intensive (and in the unpowered versions case, fuel costly,) to produce. I'm thinking something to do with rock crystal for one that makes incredible weapons/armor, and something to help boost room values. What I'd call these, I haven't the faintest clue.
Also the possibility of using a few animalman tribals to make skulking/snatching civs, perhaps. Mainly for more theif variety besides kobolds.
Any thoughts by anyone on these or the previous ideas?