Nice to hear from you! The main application that I use for QS is a chatbot called Momo and the data are entered as conversation. For instance, if the user says...
Ayer vi "El quinto elemento". (Yesterday I saw "The fifth element")
...the bot saves that and creates XML records with the date and the title of the movie. Another example, if the user says...
El sábado gasté 5 en cine en entradas para "Jumanji". (Last Saturday, I spent 5 in movies en tickets for "Jumanji).
..the bot creates XML records with the amount, the date, and the category of the purchase.
With that information, the bot can do some cool things, such as showing the info in a calendar or as statistical charts. For instance, these screenshots show some data for movies as a pie chart, a calendar, an histogram and a list.
I use a different application (also selfmade!) for storing information about workout/fitness, because I needed a more complex application, with some functionality for guiding the user through the workouts and some music to improve the experience. I have also developed one last tool for storing cooking recipes which includes some functions for storing QS data, but I only used it mainly as a cookbook.
The main idea under all these application is storing the information in a simple format, but flexible enough for rendering the information in many different ways.
I have found that the data about purchases are great for staying on a budget and deciding future purchases. I also used quite often the information about the movies I see, because I love movies and these data help me decide which movie I will watch again. I have found that, at least for the movies I like most, I enjoy better watching them again if I wait about one year.
Apart from that, I also use the bot for reminders (now I almost never miss an anniversary/birthday/date) and for storing miscellaneous information, such as the books I read, or the size of clothes. It also includes some functions for storing various lists (for instance, holiday checklists).
I would definitely love having a tester and I would love to know which data are you interested in tracking. The applications above are available and free to use, but it could be interesting in tailoring it to a real user (besides the developer).
Well, it has been quite a long answer! If you would like to know something else about these ideas, just let me know!