Most of us don't use OS X to its fullest potential. Here are some great tips for getting the most out of Smart Folders. I have several of these set up, including for System File searches, PDFs, and Preferences. It's kind of like a searching shortcut.
Want to keep track of all documents you have greater than 500MB in size? All your PDFs? All your OpenType fonts? Pictures taken with your Canon PowerShot within the last two weeks that have less than a specified focal length and greater than a specified exposure time? If you can set up a search for something in the Finder, you can make a smart folder for it too.
[From Smart ways to work with smart folders | Business Center | Working Mac | Macworld]