Here is a simple and fun way to create a drop shadow effect on the edge of an object or piece of paper. In this effect you can see the shadow cast on the just one side of the edge!
This is a great and easy way to add a drop shadow to several items without having the shadow bleed off all the sides.
Start with a rectangle and fill it with a color. Round the ends if you want by using the Direct Selection Tool, select only the 2 corner points, then adjust the corner widgets to round just the 2 corners.
Using the Direct Selection Tool, select the lower left corner and using the right arrow, move the selected point to create and angled end.
Create another rectangle, fill it with black. Make it taller than the original rectangle.
Rotate the black rectangle to match the angle of the first rectangle edge.
Make a copy of the rotated black rectangle (you will need it later and it is easy to not have to recreate it).
With one of the black rectangles selected, choose Effect>Blur>Gaussian Blur (under the Photoshop Effects section).
Set the Blur to 35, make sure you click on the Preview button to see what it looks like.
This will create a Photoshop Blur Effect on the rectangle.
Take the copy of the black rectangle and make it larger than the blurred rectangle.
Place the larger rectangle over the top of the blurred rectangle. Bring to front if needed, making sure the bigger rectangle is on top.
Select both objects. Choose Object>Clipping Mask>Make (COMMAND + 7)
With the Masked object selected, go to the Opacity Menu in the Control bar. Set the Blending Mode to Multiply.
Move the shadow over on top of the original angled rectangle. Line it up with the edge, adjust the opacity of he shadow if needed.
Select the angled rectangle, choose Object>Path>Offset path. Set it to a negative number on the offset to make a smaller shape inside the original.
With the new box created, bring it to the front.
Set the color of the new box to be lighter than the original color.
With the Direct Selection Tool, select the left edge of the new box and move it over to the right, hold the SHIFT key down to make sure it stays in line.
Add type to the pull tab and you are done! This is a great and easy way to add a drop shadow to several items without having the shadow bleed off all the sides.