1. Create a large document. Try 800x600. Make the background black.

2. Create a new layer. Take a white thin soft brush and create a few strokes. Keep them thin and separated.

3. Go to Filter Distort> Wave.
Settings:
Number of Generators: 12
Wavelength: Min: 85 Max: 576
Amplitude: Min: 21 Max: 22
Scale: 100%, 100%
Type: Triangle

(You may want to apply the wave filter a few times with different effect values. The goal is to get a bunch of strands ranging in size . If its all clumped up then you need to try again. I suggest using the zig zag and shear filters to achieve this as well as using the wave filter.)

4. Create a new layer. Take the Dark Spectrum Gradient and make a diagonal gradient. Set the layer to overlay. This is always above the brush layer.

5. Duplicate the brush layer. Go to Filters>Blur>Radial Blur.
Settings:
Amount: 62
Blur Method: Zoom
Quality: Good

6. Duplicate the brush layer again. And go to Filter>Texture>Stained Glass.
Settings:
Cell Size: Around 40 (You want to achieve the greatest amounts of cracks.)
Border Thickness: 4
Light Intensity: 0

(Multiple applications of the filter may need to be applied. To get more cells, try setting the initial cell size large, and then decreasing each time as you apply it.)

Final Result:

 

A signature Example

Discuss the Adobe Photoshop tutorials on the forums. You can find the photoshop files to download there too.