I googled "golfdust" and found a site on it. Apparently it's some stuff you can spray the ball with and it will show where the impact point on the ball was from your club. Guess you could use it to improve your swing. Looks kind of like a goofy thing to me, but there were a lot of sites listed in the search, so it must be something people use. Has anyone every used this kind of stuff as a training aid? Did it help?
If anyone wants more info on it, I'd check it out via a search instead of visiting that link, which forwards you on to nowhere.