I promised a long time ago to tell you more about the most underrated yet one of the most powerful tools on your Mac OSX: the Automator.
I’ll be speaking here about the Automator version on Snow Leopard (OSX 10.6) which, although highly similar to the one in Leopard (OSX 10.5), has a number of extremely cool usability improvements. If you haven’t yet, you should upgrade to Snow Leopard, anyways – it’s highly worth it.

You can find Automator in the Applications folder. Once started, it’ll ask you for choosing a template for your workflow. Workflow is the name of what you create in Automator, a succession of tasks you want to bundle together to.. well.. automate. Most of the times you’ll want to select the Service template: the resulting workflow will then be added in the Services menu, which appears when you click the name of any opened app in the top menu bar.

Once you picked a template, you are presented with a HUGE list of tasks you can chose from. You’ll drag them to the right panel of the app, in the logical order of your actions. Save with a clear name and, boom, you got yourself a nice little automator service.

What kind of tasks can you automate? Pretty much everything, from renaming a bunch of files, resizing pictures or changing the image types, to emailing files as attachments, make video captures from the current movie playing or automagically converting PDF files to plain text ones.

TUAW has a list of 5 pretty cool and useful automator services you can create in no time:

1. Attach selected files to a new Mail (identical to what happens in Windows when you right click on a file and select the “Send To” option)
2. Print Selected Files
3. Create thumbnails/resize selected images
4. Start Keynote Slideshow(open up a keynote presentation directly in slideshow mode)
5. Bit.ly shorten a URL(you’ll need to download a piece of software as well)

Personally, I have 3 vital automator services that I use really often:

1. Batch rename files
   
2. Resize image files
   
3. Change images type
   

Notice how I checked the ’show this action when workflow runs’. When I select a bunch of files in Finder and then chose the respective option in the Services menu, there will be a popup showing the Automator action. I will therefore be able to pick exactly the new image type or size that I want to apply, or what to change in the selected files names.

You probably won’t use Automator very often; but it’s certain that once in a while you’ll be so pissed off from having to repeat the same task over and over again (like renaming all pictures in a folder, from PICT_01_15.JPG to JohnAndMarryWedding_15.jpg), that 10 seconds spent in Automator will save you full hours of mindless repeating work. And I hope that you’ll mentally thank me for this modest but hopefully useful post.