I'm sure there will be some really creative and technical entries in the 1Hz challenge, but mine is quite prosaic: a clock! But not an ordinary clock: the "1Hz" signal is obtained by hacking the internals of a common crystal-disciplined quartz clock movement mechanism. It comes in at 8Hz, so we scale it to 1Hz with a CD4017. Then let the fun begin: trigger a real "tick"-"tock" sound generator (555/74LS73-based), alternating LEDs tied to the latch outputs, and drive a coil to get a snowman nodding along