3D Frame Effect using a gradient on the stroke (Click the image to see it bigger)
Today's effect is described by my sister as "lovely unstructured and weird", and "the colors disagree so much that they agree". Say what you want, but in either case it's a demonstration of what you can do with a gradient in the Stoke effect, as well as a bunch of other effects. Read on for more info on how it's done and to download the style file.
3D Frame Effect
Outer Glow settings (Click the image to see it bigger)
Not sure the Outer Glow is necessary, at least not for something more serious than this, but it adds its own charm to the image. It's really straight-forward, the color is set to a dark blue kinda color, and the Size is large to create a large glow.
The Inner Glow settings (Click the image to see it bigger)
I'm pretty sure the only thing I've edited here is the Size, apart from that the settings are the default, and while I generally recommend against using the default values (if nothing else, everyone else can do that as well, so you're not doing something new) I think it works out pretty nice in this case.
Bevel and Emboss settings (Click the image to see it bigger)
Now, this is a bit more interesting. The Direction is set to Down to simulate the surface bulging inwards, the Size is just a random value that visually fits the size of the object in the image. I've increased the Soften value to its maximum to make sure the transition is really soft, apart from that I've lowered the Opacity for both the Highlight and the Shadow, to make the effect less abrupt.
This is where we find today's gradient, in the Stroke. The Size is large enough for the effect to be visible, without being so big that it is overwhelming. The Gradient itself is one of the default, it's called "Copper", and I think it works really well for this effect. The other really important setting is the Style, it's set to Shape Burst, which makes the effect follow the contours of the shape rather than a pre-defined shape as with the Linear or Radial etc. (To get a slightly different effect try playing around with the Blend Mode of this effect.)