Memento Mori is a surprisingly popular topic on HN. This Wikipedia page or some other blog post on the topic gets posted here fairly often. It's kinda interesting because when I bring this up with people I know they usually say it's depressing and strange.

I like this idea so much I made an app that makes my wallpaper show what percentage of my life is already gone by, but only one person (a good friend) that I've shown it to IRL has actually liked it.

App: https://play.google.com/store/apps/details?id=com.machineryc...

Source code: https://github.com/ethanmdavidson/DeathProgress