The Five Minute Journal is actually a paper notebook and journaling technique that offers you prompts and space to write on specific things every day. For example, it'll ask you to jot down something you're grateful for, then something you've learned today, something that went well or didn't go well, and how you're feeling. Over time, you can build a good picture of the things that make you happy or unhappy, and use it to chart your mood or even pattern your behavior so you have more good days than bad. The iPhone app brings the same philosophy to your smartphone, and lets you do this anywhere, anytime.
The app will give you some writing prompts so you can jot down quick thoughts—no more than a line or two each—to popular your journal. From there, you can add things like a great photo that sums up the day for you. From there, you can share some of your moments with friends, or you can keep the whole thing entirely private and lock the app with a passcode. Either way, the app leverages the proven benefits of journaling and mood tracking to help you improve your life, and it only takes a few minutes each day. It'll set you back five bucks, but if that kind of mood tracking is interesting to you, it's five bucks well spent.