[PseudoFenton]

DF8 introduces Poisonwood and Poison Metal for weapon qualities which seem very much based around the idea of having irradiating properties in them. Not very useful for local to find them, but having a whole area which is inhospitable to normal life due to everything being irradiating, but the local wildlife as adapted somewhat could be interesting.

A few radioactive badgers, a lot of undead who don't care about cancer, and a forest of poisonwood trees and deep mines exposing poison metal veins for some evil guys new armaments for their army. A perfect area for you to strike into in an attempt to disrupt their evil plans, but really can't afford to linger in (and no army would dare to march on), although loot would be very very thin... which may annoy some, throw some ancient temples with writings on their walls which will teach you untold secrets and long forgotten (but useful) knowledge and you've got a form of loot, this also plays well into the Elder Things domain.

EDIT:
Infact, having a DF setting with large swaths of areas like this, perhaps saying poison metal is some kind of skymetal/meteorite originated ore, would be a really good reason for a bunch of violent hobo's to go about doing what they do.

Many many generations ago the gods cursed the lands and sent thousands of burning curses from the heavens destroying the sinful and cursing their lands so that none may ever enter them. In present day noone but "adventurers" are insane enough to enter the cursed lands (where all but a few races perish within days of entering, or having lasting ailments for the rest of their lives), however the cursed kingdoms of old still reside in these cursed areas, their temples and cities turning to ruin with the ravages of time. Their wealth and recorded knowledge just sit around waiting to be reclaimed for anyone daring enough to try it.
Of cause, the various "monstrous" races and badguys are immune to this curse (or have a better resistance, allowing them to survive on the edges of these areas), which is why they are now shunned when they enter the civilised worlds as they must be cursed along with the lands. They manage to survive alongside significantly more organised and sophisticated groups as no army would ever dream of trying to eradicate them in their cursed home lands, but adventurers can be hired to deal with any potent threats when they arise!
Although few people would buy or accept loot found from the cursed lands, most coins are hard to distinguish from one another so can generally be worked back into circulation, or perhaps alchemy has found a way to neutralise them of any curse they've acquired (making the alchemist guilds the most powerful forces in civilised lands).
Magical items and the like however, especially potent ones, tend to be viewed with massive distrust... fearful that they may be left as tests from the gods or assuming anything so powerful must have acquired potent curses too, as such only adventurers dare to use them. Which is why they tend to amass the power of demigods... at least until the curse starts to set in and they die a premature death. Any magical items like this which have made their way into the civilised lands but had their owner die of curses would be buried deep in tombs designed to keep others out, least they share the same fate (because who wants to put them back where they were found originally??) which makes for good low level questing sites!
There's also short cuts through monster inhabited cursed lands which cuts days or even weeks off of travel times and trade route which low level adventurers might perform, or even just the classic defending the wagons as they take the three week meandering trail between cursed woods full of ambushing monsters!

By god if I'd thought of this before I started my campaign I'd totally have done this! It totally allows much wider Fantasy elements into your DF world, politics and economies can easily co-inside with this premise! Bah, I should've kept my mouth shut and written with up as a Pyramid piece! =D