Did you know that IP-based GeoLocation is saved to the database?
Every new question and answer has geo-location data (if available by just the ip address). This data includes latitude and longitude coordinates. This means that an app or a feature can be created to plot recent questions and answers on Google Maps.
Or a single discussion thread can be presented in the form of the Map, plotting poster's avatars and intro (first 150 or so chars) on the map.
This is just a little feature that is just there - you can write your own module to use it.
I probably will not have time for this in the next 3 months but anyone is welcome to contribute. It's not all that hard - the data is already there.
Another hidden feature: did you know that a word count is recorded for every question and answer? It even works correctly on UTF-8 strings, like for other languages.
A feature can be written to calculate average length of question/answer per user, total words posted by user, etc.
This is something that is just there, and now that you know, you can use it to write your own module that uses it.
Maybe some day I will add it in here too. Does anybody want this?