Future Me - Send an email to your future self

Daylio - Daylio enables you to keep a private diary without having to type a single line.

Dabble Me - Your own private place to write. A journal/diary to help you remember what's happened in your life.

Penzu - Keep all of your thoughts in one place using Penzu. The app is similar to a journal that you might write in but with a few modern touches that allow you to do everything from sending messages to decorating the pages.

Letter to Yourself - Send a physical letter to your future self

Journey - A diary that keeps your private memories forever.