Normally, this wouldn’t quite make my radar, but [sprite_tm] built it, and it’s funny as hell. He created a Terror Level indicator for… his toilet. Rather than create an exotic smell detector, he simply uses a photo diode to measure the amount of time that the light has been on in the ol’ water closet. As time progresses, so does the Terror Level indicator. To make an audible indicator, he used the PWM generator in the ATTiny231to create a sort of ping sound when the level escalates. (I can definitely think of someone I need one of these things for.)