If you're on Android, I
Amdroid is great. Combination alarm clock/countdown timer, let's you save many different countdowns/alarms with names and alerting styles.

I use it all the time to make sure I don't forget shit. Washer and dryer each have a countdown for the length they run, along with dishwasher for the same reason.

I also use LifeUp to gamify my task list to help ensure I (generally) remember to do my daily/weekly tasks.