Timehop is a service that allows users to write about their daily lives each day and then in a year you will get en email that tells you what you were doing a year ago. So if you are someone who is constantly forgetting your past, this would be a good way to help you remember (wives I am sure would like to share with their husbands). At the same time, I could see the benefits of a site like this for people who suffer from Alzheimer's as well. If you login or connect to Facebook, Twitter, Instragram, or Foursquare, it will add in memories from those services.
This would be an interesting service for students to use to help them see if they reached a personal goal or write about experiences in school and think back to how much their opinions and friends might change within a year. The only negative is that right now, it does require Facebook to use, but it would still be a neat writing experience.