Lee Hoffman has created a free iPhone app called "Memoir" that reminds you of the past. At its simplest the app shows the digital diary of what you were doing on past days, but also permits the annotation of photos with location information and personal thoughts and opinions. "Memoir" also tries to remind you of past memories when you return to specific places and meet people, nudging you with notifications and updates to your "Memoir" feed. If you go skiing, it may, for instance, remind you of a photo you took the last time you were on the slopes. The app also encourages collaborative memories, so if you have any Facebook friends who are also using the app and you happen to be taking photos at the same event, the app will suggest that you share them with each other.