Net Effect

Make a new document sized 300x300 and fill it with any color. Now grab your gradient tool and using the settings below:

Click to enlarge

Start drawing until you get something like this(the result will always differ) :

Now go to Filter>Stylize>Find edges

Press Ctrl+I to invert the image :

Go again to Filter>Stylize>Find edges

And again press Ctrl+I to invert the image:

To remove those ugly colors press Ctrl+Shift+U to desaturate the image:

Duplicate the layer and set blending to screen and lower opacity to 40%. You should have something like this :

Press Ctrl+U to give color.

I used a simple blue color:

You are pretty done. For a better effect I duplicated the layer and added a crosshatch(Filter>Brush Strokes>Crosshatch). Now set blending to overlay.

This is my final result: