Adding Gold Find
Adding Gold Find (or GF) to your character aids you in finding more gold from monsters and item drops as you adventure. In and of itself, it provides no useful benefit, and can take up a slot on your equip that could be better put towards keeping your character alive or allowing you to dish out more pain to those evildoers.
Diablo III has many ways to obtain additional Gold Find. You can find it on your equipment, apply it from shrines you find, add stacks of Nephalem Valor, add Monster Power to increase it, play with more players to get a little more, increase your Paragon Level, and even socket your helmet with an Emerald to get just that little bit more ... But Diablo III also introduces the concept of a Gold Find cap. Your combined equipment (plus 20% of your follower's Gold Find) and your Paragon Level cannot exceed 300% GF. All other effects can apply to increase your Gold Find over the cap.