Saturation curves (link to photoshop action)
This will be useful for punching up saturation without blowing things out--similar to pulling up the curve in an imaginary saturation channel. I'm sure people here will come up with more creative uses for it!
Is this what the vibrance slider in ACR or lightroom does?
|From Maroon to Yellow by Azrocin|
from Fall colour
|Mandarin Duck by gordzam|
|Porsche 918 Spyder by rmw18k|
from Sports car