This is an idea I found when looking through my email. I originally sent this to Oog, another person on the team.
An optional location, but there's a mighty big sidequest here. EVERYONE in Dusk seems to be out of their mind. For example, there's the kid with the gas mask asking if you're his mummy, the gravekeeper/butcher, etc. Basically, the whole town's fucked up pretty bad. Your job is to find how it became this way, and how to turn it back to normal.
Keep in mind however, a store in Dusk sells some very... interesting equipment. The equipment's effectiveness increases with the amount of kills you've ranked up. Still, all this stuff's rather expensive, so if you want to get the equipment, you might want to "purify" Dusk a bit later.
Once you purify the town, it will quickly grow, becoming something very different. The poor people will move in, making the place their own. They have pretty good prices on everything, but not all of it's top quality. Still, there's a way to rectify that, by donating to the "Rebuild Dusk Fund". Others will occasionally donate as well, but you'll have to do most of the spending yourself.
Partially inspired by the Doctor Who episode "The Empty Child". Do a search for it on Google Video.