Local, non-destructive changes to saturation

[short sail]

Howdy. I once considered myself an advanced user of Photoshop but have been out of practice for several years. I know there's a way to make local, non-destructive changes to saturation (because I used it extensively in the past) but have forgotten the method (I'm not referring to a hue/saturation adjustment layer).

This would be similar to the method I use for local, non-destructive dodging and burning: an independent layer filled with 50% gray and set to "overlay." Dodging an area lightens the layers below in that spot, burning does the opposite.

Anyone have ideas on how to do this?

[short sail]

Now that I'm thinking about it, it might be helpful to rephrase:
I'm looking for a way to non-destructively sponge. I can't recall if my past workflow used an adjustment layer with a 50% gray mask upon which I dodged/burned the mask or if it was a layer upon which I painted/dodged/burned directly.

[lunar smelt]

Do you mean the smudge tool? You could duplicate the layer and smudge the new layer.

[rain iris]

You can get that by performing your sponge on a neutral grey layer (probably set to overlay, but check this one out)
I would really use adjustments layers though, that I can mask, or the new tool, the adjutment brush (that creates a new adjustment layer with a mask, based on your brushstoke)

It's available through the contextual bar, choose the brush tool, and click on the yin/yan icon for adjustment layers and you'll get access to the adjustment layers panel. Choose one, and now everytime you draw, you'll "paint" an adjustment layer (the result is still a separate adjustment layer though)