Sway 3D object on Z-axis using slider?

Hi there,

I have multiple objects (side by side) which I would like to sway on the z-axis as if the wind is blowing them.  I already have their anchor points at the top of each object.  I have a few issues:

1. I have multiple objest which I would like to have random movement on.  I don't want ALL objest to sway to the left, then ALL sway to the right.  Rather I would like them to be somewhat random/organic.
2. I need to be able to control all of them with a slider...  I would like to be able to turn the sway up and down and ultimately have them all come to rest at a still position (with 0 z-rotation).
3. A slider would be ideal as I would like them to gradually stop swaying, not just "on" and "off"
4. There are about 15 objects to sway.  If there is no way to randomize them I would be happy even to make multiple slider controls so that object 1, 4, 6, etc. would be controlled (and have identical movement) by 1 slider, then objects 2,5,7 etc. would be controlled by another, and so on.  I suppose this would simulate randomeness but would not be ideal.  I would like the slider conrol to be dead simple.

Any thoughts?

Thank you very much!

-Stephen