I thought I'd show you my mods on cool gradient backgrounds in Photoshop.
The tutorial I found on the web: Photoshop Gradient Background
I have a couple things I like to do. You do not need to use just angles on a linear gradient. You can also use the diamond, radial and circular gradients.
A really cool idea is to create a gradient with a very narrow band of color on one end (White at 0, Blue at say 5, and Green the rest of the way out). This makes a circle that looks very 3D, and yet has not implemented the emboss tool.
Another one of my ideas is to create 2 completely different style layers of the same technique. Then set the top layer blending mode to difference to get double the effect. You could also use any other blending mode, such as hard mix.
Put a photo on the bottom layer, a gradient layer over that and set a blending mode on the top layer.
Here are some pictures that I created using these techniques:
My Photoshop Web Album
Note the "Sister's Creation 3." This was the type I was talking about above, where a tight gradient on the end would make a pseudo-emboss.
Also note the "Chrome Flares." This was using another technique where you create multiple lens flares on a black layer, and then chrome filter the layer. I then did an Pin Light or Hard Mix (I can't quite remember) of the gradient layer onto the Flare Layer.