A few weeks ago at the CMU iOS App Challenge, following the release of Swift and Xcode 6, Ally and I created a Mindfulness Journaling app, which you can view via the GitHub and ChallengePost links above.
Mindfulness journaling is all about non-judgmental observations of both the external world and the internal experience of thoughts and emotions. To help with this aspect of journaling, the New Entry view has, along with an empty text box, the option to create a list of observations and their intensities. For example, along with my journal entry, I could add an observation of Anxiety with the rating 7/10. As we further develop the app, this type of data can be used to track anxiety levels over time, or to track the frequency of various observations.