I have made an application for Facebook. It's called Mood Tracker. It sticks a little chart on your profile that tells people how happy you are feeling. You can tag your moods to develop an idea of what makes you tick, and see a list of how your friends are feeling.

It's something I've been kicking about for ages - last year I was working on this concept but it was more extravagant and featurey. The user model became a problem and I never really got it working very well. However, I did use it myself for a while and I found it had a lot of value in helping me understand what makes me tick. When you are asked to quantify your happiness, and it comes out low, you have to start thinking about why. This is a good way to break out of the numbness of depression - you can see that you used to be happier, you realise that something is wrong now, and you can try to do something about it, instead of remaining in that weird resigned oblivious mindset.

Ratings can be tagged. This is a good way to get an overview of what you should pursue, and what you should avoid. The unhappy tag cloud is hidden by default.

I will be focusing on enabling more input channels for this application next. It is important to be able to report your mood at any time, and another key feature of the application is that you will be ASKED from time to time how you are feeling. This means you are more likely to record data for moods when you might be less inclined to be thinking about what your mood is.

Feel free to install the app here: Mood Tracker - I hope you find it useful.