You know that building with a blindingly empty wall that is still safely untarnished by Eva Mendes' Calvin Klein lingerie clad body? Don't you sometimes wish there is a way to put your artistic two cents on it without going through the hassle of actually buying enough paint for a large mural on the space and running the risk of vandalism? FatTag has the brightest (quite literally!) solution to your creative impulses, and it involves just a little bit more than FatTag, a graffiti tagging iPhone application which enables one to tag within the comforting screen of your iPhone and set it against multiple backgrounds or images you have captures, and a projector. The detailed steps (with a little manipulation with a private Apple framework) to marking the building with your iPhone is chronicled at the F.A.T site. For those interesting in testing the creative limits of your iPhone, click on over, take your iPhone for a trial run and enjoy seeing your handiwork on any building you fancy. As for the rest who are not quite convinced, enjoy the video before borrowing your neighbor's projector. The FatTag Deluxe app is available to download and peruse here.