Postal Stamp
This trick requies Photoshop 7

1. Create the basic image for your stamp and add a Quick Border around it.

2. SETUP THE ERASER TOOL: Choose a large size Hard Eraser and set the spacing to ±150 in the "Brushes Tip Shape" Menu.

3. CTRL+Click on the Layer to Select the rectangle image.

4. Go to the "Paths" Menu and choose the "Make Work Path" option.

5. Make sure the Path is selected and go to the "Stroke Path" menu (small right arrow in the Paths Menu) and select the Eraser as your tool.

6. Click OK to create your stamp.