I was wandering through the MI forums when I stumbled upon a wind rig prank, but that's irrelevant.
While I was reading through the comments, I had an interesting idea:
Wind Paths: A line of sorts that can be moved around to direct the flow of wind along that line. It would have a Radius that controls to what extent from the line the wind is effected. The path itself would have a number of points that you can drag around to make a more complex path.
This could be used to make a valley seem to have wind rising up it's sides while having little wind in the center of the valley. It also could be used to give the effect of swirling grass.
This might have been suggested before, but as far as I'm aware of it hasn't.