While the Luminance Curve doesn't have as many practical uses as the others, it is particularly good at sky adjustments. To darken or add contrast to a sky, it works a little better than a key because you can build...
The "Hue Curve" in Apple Color works like the Sat. Curve, but shifts the hue of the selected color based on your points instead. The Hue Curve is actually great for emulating old stock, like a two-strip process. Just like...
The saturation curve lets you adjust saturation for a range of hues using control points. Isolate the hue, then pull up/down. It's particularly useful for affecting multiple colors/hues in a single secondary. The best way to describe how this works...
Want to affect everything but something? Key or put a window on what you don't want, then work "outside" your selection. In Resolve, make a new "outside" node. In Apple Color change this drop down: I used this technique to...