In OS X, you can always toss a file onto the command line instead of laboriously typing out a complete path name because Terminal supports drag and drop. Over at Murphymac, Murphy has posted a video showing you how to create a shell script using DES3 encryption to protect your files. It takes advantage of this drag and drop support so you can basically run the script and drop the file you want to encrypt. Even if you're not all that interested in encrypting your files, this videocast shows how to think about creating shell scripts with a particularly interactive OS X flair.