These videos are increasing order of detail. The first shows you how to get started , Julieanne's shows some interesting possibilities and more advanced action possibilities and the rest are about creating useful actions for photographers.
Try this if you want to explore actions more.
Create watermarks in Photoshop.
Create a Watermark Brush with text.
Create a watermark brush with a signature.
Use a pen on a piece of white paper.
Scan the signature or use a smart phone to capture it.
Create a transparent copyright watermark.
Create watermarks for both portrait and landscape images at their maximum width.
Create actions for using the watermarks.
Create an action to Place a watermark for either portrait or landscape photos. Use Conditional Actions.
Create an action to save as a JPG for your web site that will resize a portrait image to 600 pixels and a landscape to 1200 pixels.