Splashy - Breathtaking, auto changing wallpaper app for macOS, Windows, Linux, iOS & Android
Future Me - Send an email to your future self
Splashify - Beautiful desktop wallpapers for Mac and Windows
Dabble Me - Your own private place to write. A journal/diary to help you remember what's happened in your life.
Irvue - (previously Unsplash Wallpaper) Gorgeous wallpapers on your Mac.
Letter to Yourself - Send a physical letter to your future self