Custom Shaped Drop Shadow
Give your photographs a unique style with a custom drop shadow.
In this tutorial we will be creating a custom drop shadow for a photograph. This drop shadow technique allows for greater control over where the shadow actually lands and provides the opportunity to add some cool effects to photos.
Well, lets get started!
Create a document in photoshop and import your photograph onto a new layer. An optional step is to add a colored background to the document.
Add a layer below the photograph and with the rectangle tool draw an off-white border for the photograph.

With the pen tool create a shape that curves in at the center of each side. Have the foreground color set to black.

Relocate the black shape's layer behind the white border's layer and add Guassian Blur to the black shape's layer. (Filter > Blue > Guassian Blur).
You will need to adjust the amount of blur and its location underneath the photo in order to get it looking just right. In addition, you might want to use the freeform tool to alter the dimensions of the black shape so that it lines up with where the shadow might realistically fall. .

If you want you can change the angle of the photograph by selecting all the layers containing the shadow, white border and photograph. I select the layers I want in the layers window by ctrl clicking each that I need. After selecting, rotate the photo to the desired angle.

Ohh! How nice! We're finished!