Recently I was offered a snake and a terrarium. The only way to light the whole thing was to use a lamp or LEDs that you connect to a timer. 
Well the principle is functional and energy efficient in case of LEDs but it did not reproduce completely the real conditions of illumination.

So I had the idea of ​​developing a board that could control the lighting of my terrarium in several ways:
- Lighting control according to a "classic" mode, based on time slots.
- Lighting control according to the real curve of the sun based on geographic coordonates.

As I was developping this project I realized that this board could also be used for other applications.
For example we hear a lot about circadian light cycles nowadays, I think this board could be a good start for this kind of use.

The other use case that I have personally studied is controlling horticultural LEDs (simply changing the led board).