DIY [picture hanging]

Do you ever come across something online and think... Duh, why didn't I think of that? Well, today is going to be another one of those days. How many times have you measured, nailed, hung and rehung (and rehung again) a photo on the wall? Dozens of times here. Well, today is your lucky day. You will never ever have to relive the horror of hanging again, thanks to this little gem we found...