This is made from one of the brushes that comes with PS CS5. I made the left half dark davy blue and the right half a bright orange. I then used the mixer brush picking up extra color from the layers below. I drew it right down the line between the two colors. Than I made many layers of this drawing. I varied the the layer opacity to give the layers some depth.
Toward the finish the Watercolor filter was used. I always up the Vibrancy and probably the gamma in each piece.
If you have any questions please ask me.