You know, I thought I'd seen the ultimate in Iron Man cosplay last year, and from a decorative standpoint, I probably have. But Anthony "Master" Le's outfits don't shoot real lasers like this thing does.
AnselmoFanZero from Laser Gadgets has built this incredible "Functional Iron Man Laser Gauntlet", which does exactly as it says. It looks like Iron Man's arm, and it shoots a real laser. Maybe not one that can blow up tanks, but it can blow up... balloons.