CPAP machine. If you think you may have sleep apnea then get it checked out.

In-line water filter. Reduce the barrier-of-entry to drinking water however you can. Started with one of those gravity filters but having to refill it all the time was a barrier. One that's tied into mains pressure just works.

Ceiling fans. We have an evaporative cooling system which is good, but adding ceiling fans in the bedrooms and office really allow good air circulation on those hot days.

12mm flashing red LED and a magnetic switch. Stuck the magnetic switch on the garage door and the LED in the ceiling by the front door. Can now easily see if the garage door was left open.