Now that even CSS3 supports programmatic shadows you may feel the need for a more unique shadow. You could use it on a website or on a presentation. In this post I'm going to teach you a technique on how to create a shadow with your own signature look. I have created this tutorial on the Photoshop CS4 Trial version by Adobe.
(1) Create a new file with 1000 x 1000 pixel dimensions.
(2) Make a light greyish background to better highlight the white paper on which we're going to apply the shadow upon.
(3) Create a new layer and inside of it create a white paper like shape.
(4) Copy the white paper shape layer for later use.
(5) Apply a shadow with the values like in above screenshot. Opacity: 26%, Distance: 6px, Size 32px
This is what your layer setup should look like by now
(6) Set the fill value of the white shape to 0%. This leaves us with just the shadow.
(8) Now the creative part starts: Pick the eraser tool, set it to a value of your liking. I chose 87px diameter equipped with a smooth brush. I set the opacity to 35%. Awesome: the second white layer that we created in Section 4 earlier will be left untouched by our eraser action.
(9) Now utilize the eraser tool to make the paper shadow look unique. As last action merge everything except the grey background et voila - a nice unique shadow effect.