Stop Using Curved Drop Shadows
delvarworld.github.com
delvarworld.github.com
Popular example: The new Ars Technica Design: Background - light from the bottom; Social Icons - light from above. (There are worse examples out there but this just came to my mind first...)
For example if the image portrayed is particularly detailed/noisy, then it's ideal to distort it to lend to the fact that the edges are curled towards the viewer (a weaker version of how a label around a cylinder appears distorted.)