Not sure if anyone has tossed this out there yet.
An underground occurrence, like lakes, caverns, spider nests, demon forts etc.
A large circular occurrence, spanning a few Z levels, containing two or three dragons. At the bottom, a pile of gold items (goblets, coins, flasks, weapons) and some cut gems.
And they could have a tribe of kobolds enlisted to enlarge their hoard with shiny stuff.
Y'know, that's not bad. Or dark gnomes, or "drakelings" or something. You start a fortress on an embark site, and suddenly you notice a specific type of critter in the fort going after the stockpiles of gold and gems and such. You know then there's a Trove or Keep somewhere below.
I really brought this up because Dwarf Fortress, while dwarvenly, doesn't seem -greedy- enough. Sure, you're judged by your wealth, and the valuable makes any sane dwarf happy, but it's almost as if the rest of the world has forgotten you're tapping into rich veins of everything over here.
Thieves are sparse, goblins are just bloodthirsty, and humans seem peaceful and co-operative.
I want the game to be really centered around the -horde-. The whole fortress built around the most heavily fortified location: the vault. Where if you make golden goods, you best hide them away 'lest word of wealth rises, and sieges occur from legions of shadowed thieves.
I don't know. I like DF as it is, but it seems too set on the survival and well being of the dwarf through shiny things, now the well being and acquisition of shiny things through dwarfs.