Automator is another great productivity tool that was introduced with OS X 10.4. I've always been a fan of Applescript so I was no stranger to workflow automation, but Automator took things to the next level as far as accessibility and simplicity go.
One of my favorite Automator workflows makes the task of renaming a group of files extremely easy. In fact, creating the workflow itself is a piece of cake too.
Open Automator and choose these two actions:
Set them up like so, and under "options" on the second action be sure to click "Show Action when Run". Then select "Save as plug-in" under the "File" menu, and choose a name for your new workflow. I chose "Rename Sequentially". Now click save.
Navigate to a group of images or documents or whatever that you would like to rename, select them all, then hold "ctrl" and click on them. You should be able to select the workflow you just created through the Automator menu like this:
You should now see a display like this:
In the field where you see "untitled" put a word that describes all of your photos, something simple like "vacation06" or "jims_bday". Click continue, and watch all your files be magically renamed right before your eyes!