Close garage door or verification it is closed. Turn off outlets (parasitic devices or just something I forgot). Drop water heater temperature when away assuming not tankless. Pet feeder/treats. Close/open shades depending on temperature and time of year. Water shutoff (burst pipe? leaky toilet? bad neighbor?). Watering plants (bonus if based on soil moisture). Run dehumidifier based on moisture. Control ceiling fan speed in bedrooms rather than air conditioning entire house. Turn off gas if pilot light goes out (furnace, oven). Warning on radon, CO2, smoke, etc
Of the above, the dehumidifier is one that I'd really like living in Minnesota. My dehumidifier's built in threshold for running is poor so I use a timer. It is far from optimal.