My idea for a unique scent system.

Areas emit smell, not creatures/objects themselves. The longer a creature stays in an area, the more the area will smell of that particular species. The presence of several creatures of the same kind will cause the smell to grow stronger faster.
Scent won't lead you directly to the bush your prey is hiding under, instead it will just give you an idea that prey (or danger) is close.

Add a scent-carrying wind direction mechanic to this system, and you have got a pretty cool hunting simulation.