Mini Diary - Simple and secure journal app
Letter to Yourself - Send a physical letter to your future self
Grid Diary - The simplest way to get started with keeping a diary
Future Me - Send an email to your future self
REFLECTLY - The world's first intelligent journal
Letter to my future self - Letter to my future self is a prominent email scheduling service that gives you the opportunity to create a letter with goals and thoughts for your future self and schedule a date for sending it.