Mac OS X 10.4 ships with Automator, a powerful workflow automation tool that lets you easily automate the operation of any AppleScriptable application. While Automator can control many applications right out of the box, it lacks the ability to automate Photoshop. For Photoshop control, you need The Photoshop Action Pack, which provides everything necessary to drive Photoshop CS and CS2 using Automator. This updated version adds support for Camera Raw files, new non-destructive editing capabilities, Save for Web, several new actions, and a few important bug fixes.

While I'm not on 10.4 yet (some weekend soon, I have the install kit ready and waiting for me to have time for it), this looks like something that any Mac using photographer could make some great use of.