Michael notes Bill Bumgarner's example on using Mac OS X 10.2.4's new PDF Workflow feature. I tried out Bill's example, since it plays into my own web reading habits, and it's wicked cool. Bill also says:

"But PDF Workflow is even more flexible than that. It isn't limited to just saving PDF. You can also drop scripts, apps, filters, and other mechanisms into the PDF Services folder. That'd be the Workflow part of the whole thing."