The first part of Everyday Actions in Photoshop shows how to create a very simple action to add a Drop Shadow style to a subject, and then separate the shadow and move it to its own layer so you can modify the shadow in ways a Layer Style won’t let you.
"Actions have been a part of Photoshop for decades now, but many people simply fall into the habit of performing the same steps over and over without ever thinking of recording an action. However, short actions are easy to record, easier to run, and automating ordinary tasks leaves you freer to create. Over the next two articles, I’ll show you how to record, edit, troubleshoot, and save the steps you need to take every time you want to transform a common drop shadow into a realistic shadow, such as one that falls on the ground and not the wall. The action itself, though short, demonstrates the basic skills you’ll need to write similar actions that are useful to your way of doing things."