[PrinceDark]

Hiring NPCs to mine for you. Lets say you got 3 bums wanting to mine for you. Suppose each bum will mine and obtain certain types of rocks based on their materialistic appeal and work ethics.
Bum A, will give you 20 different items found, for example he gives you 12 pieces of fools gold, 1 real gold piece, 2 diamonds, 4 pieces of gralats, and a rare artifact.
Then Bum B, gives you 5 items, but 3 of them are diamonds and 2 being real gold.
Then Bum C could be a sick workaholic and give you 60 items, half crap, but the other could be of every type of item allowed.

Just an example for you to expand on.