A first for me: designing a circuit board!
One of the more noble uses of electronics: enabling the production of beer. Chillmon is a concept originally created by Eric Stein to use a Raspberry Pi to control the fermentation temperature of beer at Pumping Station:One. It began life as a breadboard that used TMP36 sensors to record the temperature in the cabinet where we ferment, with Python code that graphed the output on a web page and responded to IRC queries with the beer temperature.