Come on Snow--
EVERYBODY knows that the equation for terminal velocity is the square root of (2mg)/(DrA) - where m is mass, g is acceleration due to gravity, D is the drag coefficient of a penny, r is the density of air, and A is the cross sectional area of a penny. The drag coefficient is about .5 for spherical objects and as high as 2 for irregular objects. I will assume that the drag coefficient for a penny is .15 (this takes into account its flat and edge surfaces). If you give the penny a surface area of a sphere with a a slightly smaller radius than the penny has. The penny will be spinning as it falls and thus will not fall exactly as a sphere would, but it will not fall edge-wise the entire way either (or face-wise for that matter). With these values... the penny will have a terminal velocity of 35.1 m/s - or about 79 mi/hr. If you think a penny traveling at about 80 mi/hr will kill you, then you're crazy. It might really really hurt, and break your skin, but you would not split a person in half.
......that's the best I can do without pencil and paper.LOL