Vue has a pretty cool little feature where you can make plants grown close to other objects or thin out in shady areas. 

If you have Digital Carver's Guild Terrain Tools, you can do the same thing in Carrara with the Intersect Shader feature and the Surface Replicator. 

The uses are pretty vast, dropping fruit under trees, adding garbage next to buildings, gathering crowds around objects, etc. The nice thing is, you can also hide the object that creates the intersection – so having people all gather like a crowd around a podium means you could simply drop a cylinder into the scene, designate it as one of the intersect objects, then un-check the visibility and magically, a gathered crowd. 

The best part? You can move any of the objects around and simply click "shuffle" in the Surface Replicator and everything reorients to the new location

Pretty fun.