Sketch cards are small, 2.5 x 3.5, convenient pieces of Bristol board you can fill with a sample of your artwork to give to whomever you choose. They're best because you can exchange something other than the standard customary business card. I personally exchange these to artists with my information on the back...
So the designs got better as they moved to the right. I even started writing my thoughts down. I don't know if I can beat the original design, but the designs on the lower right are pretty good too.