MarsEdit - MarsEdit is a desktop blog editing application for the Mac. It provides an offline interface to most popular blogging systems. WordPress, Blogger, Tumblr, Movable Type, and many other systems are supported.
Future Me - Send an email to your future self
Desk - An award-winning & beloved desktop publishing client, exclusively for OS X.
Letter to Yourself - Send a physical letter to your future self
BlogDesk - Blogging should be simple, but it gets complicated and time-consuming if you are serious about it.
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.