Wow, ya learn something new everyday. I didn't even know that that low, grating tone that you put on the end of words sometimes even had a name, but apparently it does. The New York Times introduced me to the subject in an article about linguistic novelty among girls. Unfortunately, it's difficult to describe vocal fry, but you know it when you hear it. Here's a Youtube commentary on vocal fry, including some examples. In my experience, vocal fry seems to be an affectation to suggest sophistication, doubt, frustration or sarcasm.