I recently came across this conceptual design ink calendar by Oscar Diaz a couple weeks ago. It was shown at the sueños de un grifo (dream of a tap) exhibit in Madrid in 2009, but having not come across it until recently myself, and how amazing it is, I figured it was worth well worth sharing. Not only is it graphically and typographically stunning, but how it works is even more of a marvel. The ink is slowly absorbed into the embossed paper, marking each day until it is filled at the end of the month. Giving the "perception of time passing and not only signaling it." The colors of the ink for each month are chosen based on our perception of color during that month, for example dark blue in December. Love.