I know some of you are just getting started with using gradients, so you may not be aware of this neat little trick. I wasn't for the longest time!
When you go to LAYER > NEW FILL LAYER > GRADIENT this box will pop up.
Click on the box that says GRADIENT. When you do, you will see this box pop up.
Now to the right of where it says PRESETS there is a symbol that looks like this:
Click on that symbol. When you do, it will bring up a variety of Gradient presets.
Just click on the various presets and play around. My favorite is PHOTOGRAPHIC TONING.