In the Underdark there exists many mercenary companies. Given the rise of the dread empire, and the destruction of quite a few homelands it stands to reason that a number of individuals have banded together sheerly to make gold for themselves. A mix mash of monsters and depraved individuals that desire gold above all else.
Concepts include
1 Drow of Traensyr that do not hold any desire to convert to Ghaunadaur.
2 Duergar striking out to make it rich. Survivors of the broken shields/Tigereye Mercenary company
3 Survivivng Lizardfolk of Szzltech that have no homeland of their own.
4 Numerouse tribes of monsters that have lost their tribes to other adventurers or the dread.
5 Ogre Slaver of Sorrowfeast Isles
6 Half-Drow finding no respect from humans or Drow choosing the mercenary life style.
7 Svirfneblin of Urdlen exiled and rejected by most of their kind finding their bloodlust embraced by such a depraved mercenary company.
non app concepts include
1 Former worshipers of great shadow death striving to earn enough gold to gain a position of respect for Etorix/the next dragon they meet.
2 Goblins wishing to make a name for themselves to be as great as Colonel Spittlefire.
3 Slave soldiers of any of the above groups (Should be in the minority) that have found great progress and wealthin spite of their enslaved status.
4 Depraved slavers from the surface that came to the underdark after being wanted by authorities. (Preferably humans or halflings.)
This isn't just a "Quest grind concept" there shall be very realistic IG goals worked towards. Also there shall be a lot of conflict being monstrous races. In short if you're a no conflict and passive towards PVP this probably isn't a really good concept for you. (Although scummy quartermasters and fencers that have no problems selling stolen goods and hanging with monsters might be the exception.)
I dig this, i'm in, find me on IRC