I was using PhotoShop a long time before I read about Actions. If you need to resize a whole bunch of pictures, or de-interlace a whole bunch of pictures, add a filter, apply a saved curve, or whatever, put a copy* of all those pictures into a special folder and create an action. Then let PhotoShop apply that action to your folder. (I always keep a folder of the originals and make a copy w/ the effect I need.)

Ready? Go to Window > Actions to open teh Actions pallette if it isn't open.

Now click to the twirl-down menu at right and pick New Action:



Name your action & click Record:



Do everything you wish to automate. In this example I resized and then used a filter. When you are done, press stop at the bottom of the Actions Pallette.



Now you will apply this action to your folder. Go to File > Automate > Batch as shown below:



In the Batch window, be sure to pick your action, pick your folder, and choose the Save & Close option. See below: