My favorite is a script not a automation exactly. I run it (just before I get up for bed) via dashboard button or voice command and it:

• shuts off most of the lights and any screens around the house
• sets the thermostat to bedtime mode
• waits 5 minutes (time for me to get my stuff and get to bed) then
• turn off the remaining lights outside my bedroom
• Calls my autoremote endpoint

Auto remote then triggers a tasker profile that makes my phone

• turn on DND
• set media volume for sleep music and alarm volume for morning (just in case either has been change during the day)
• set a variable that another tasker automation will see the next time I plug in my phone. At which point it will:
  • set my screen brightness below 1%
  • turn on sleep tracking

Washer voltage goes from a high value to a low value, then in 30 minutes (when the cycle will be done) turn an rgb lightbulb in a conspicuous location a hellish magenta. No more funky forgotten loads of laundry. Passes the partner test, too.

Less of an automation and more of a scene control, but I have all my light switches set up so that double tapping them up or down turns on or off all the lights on that floor of the house. It’s simple but we use it all the time.

If the furnace starts pulling more than 4,000 Watts, I get a telegram message that the auxiliary heat is running instead of the heat pump.

I have a sensor in my kindergartner's bag that lets me know when he gets to school and when he leaves school, also via telegram message.

If someone loiters around my driveway for more than 30 seconds, I get a telegram message with an image.

I haven't said it back up since I moved but I used to have one that used a combo sensor my washer and dryer doors. If the sensor moved enough for long enough it set a flag that the unit was running. If it want from running to not running for a long enough period of time, and the contact sensor wasn't tripped, I would receive alerts every 30 minutes or so that the clothes were done and still in the washer/dryer.

Even something as simple as water sensors under the sink if saved my ass. Cabinetry these days is made out of fiberboard and if it stays wet for more than a couple of hours it does horrible things.

I have a binary sensor that turns on when I'm away from home for 30 minutes and off when I'm home for 5 minutes. When I open the door and the sensor is on, music starts playing and the living room lights turn on. Love it.

The hot water pipe to the kitchen is quite long. We have a pipe loop there with a pump. Back in the days we had an ordinary timer that let the pump run at the usual times when there is hot water demand to be expected.

I now use a Zigbee plug for the pump and added a button in the kitchen to start it manually. In addidion HA starts it in the morning and every time when somebody comes home. Another HA automation turns off the pump after 3 minutes and ensures that it does not start again for 30 minutes.

My favorite is turning on the bedroom lights when my alarm goes off :)

I have a motion sensor in the bedroom that turns the light on when you enter it (or leave it) and turns it off after some time once there is no motion detected anymore. But there is also a button right next to the door which disables the automation for 10 minutes for entering the bedroom at night when our youngest is already sleeping in the room.

Simple but very useful and even my wife likes it alot.

The simplest automations are the best. An hour before I typically get up, if the bedroom is too cold, turn on the heater.

Not really common automation for HA, but I made medication assistant automations. Its super helpfull for people who take loads of meds. It tracks how many pills left, does android notifications or sets alarm and it also sends an email when its time to reorder meds. Its insane how usefull it is

15 minutes before my alarm or my partner's goes off, the bedroom lights start to gradually fade on for the next half hour. A few minutes after that the HVAC gets reset to daytime temperatures. The hallway light turns on before we get out there, and if it is still dark outside (this time of year in Canada!) the entrance lights and kitchen lights also turn on ahead of time. Lastly it gets the dehumidifier started for the day and turns off Night Mode across all my automations.

Usually it results in us waking up gently, a bit before our alarms and we can turn them off without any blaring sounds.

I have door sensors on all the external doors, if a door is opened then turn the heating off. This helps over the winter when we have a firepit going and the kids are in and out every 5 minutes

Sunset and sunrise automations. Lights on and off, vacuum run times - all adapted to presence.

Made the litter-robot auto-repair when it enters trouble states. Better history of all elements controlled.

HTML scrape of CUPS web server to see if there's a print job waiting, turn on tasmota plug for laserprinter, then turn off in 5 minutes to save power.

It's an old LJ4000 so it's idle power is pretty high.

I have all the TV inputs automated via voice commands. Eg. If you say "let's watch plex", tv turns on if off, input switches, HDMI switch changes, and Plex launches on the shield.

No automation to share at the moment but the "weather lamp" is a really fun idea!

The problem with a good running automation is you end up used to them, I forget they're even there most if the time.

I end up appreciating my once-in-awhile automations more. A couple times a month I need to get up extra early, skip my normal routine and go straight to work. But I'm American, this can't be done without coffee. The night before I prepare the coffee maker and scan an NFC on the top that turns off the plug and waits for my next alarm, then turns it back on. Once it runs it disables the automation, so I dont accidently burn the house down. Worth a million bucks

In the summer in the northeast US most evenings are cool enough to sleep with just a fan in the window. For the nights that stay too warm past bedtime I scan an NFC on my AC that triggers an automation to shutoff the AC and turn on the window fan at a specified outdoor temp. Saves on electricity and who doesn't love fresh air??

• if the sun has set and my partner isn't home from work (phone not connected to WiFi), turn the hallway light on
• close the blinds when the sun sets, but only if the TV isn't currently on so as not to make noise during a TV programme
• when I turn the bedroom lamp on, turn the bedroom ceiling light off
• if my front door opens when neither me nor my partner are home, send a snapshot of the doorbell camera to my notifications