The most common use of Gradient Map adjustment layers is for black-and-white conversion, but they are capable of all sorts of cool stuff. Let me show you how to add colour and tone effects to your photos using Gradient Maps set to "Soft Light" mode.
I've used Photoshop Elements 9 for all the screenshots in this tutorial, because I never want to miss an opportunity to show Elements users how powerful their software really is. Needless to say, these methods also work in Photoshop, as well as all older versions of Elements.
As the subject of this demonstration, I'm going to begin by applying that purply-orangey look with which the industry is saturated right now. I know you love it, but mark my words, it's this year's version of Selective Colouring. Remember how cool it used to be create black-and-white images with one element in full colour? How many of those are still in your portfolio? Anyway, I digress ...
Here's a photo of my son, to which I've done a bit of basic clean processing, using a Levels layer and a Hue/Saturation layer:
For best results, ALWAYS do your clean processing first. If you don't, you'll never get consistent results from your artistic processing, and it will drive you crazy.
To begin, add a Gradient Map adjustment layer. Layer > New Adjustment Layer > Gradient Map