I started using OhLife, a free journal-by-email service, in October of 2011. Every morning I received an email asking me about my day and showing a snippet of my past journal entries. I just had to reply to an email in order to add an entry. I was very sad to hear, 3 years later, that they were shutting down. Fortunately a pile of OhLife clones have popped up to take its place.
My favorite is MyLife. It is free and provides an experience similar to OhLife. It runs on Google App Engine so there is little risk of the service going down in the future. Setup takes a bit of effort, but the author has provided step-by-step instructions.
MyLife is written in Python and is open source. I’m not great at Python but the code is straightforward enough that I was able to submit a bug fix. It should be pretty easy to add additional features if you’ve always had the itch to customize OhLife to fit your exact needs.