Here's a neat project I made to automatically adjust your monitor color temperature based on ambient light. Think of it like a hardware-based version of f.lux; instead of guessing the color temp in your room based on location, time of day, etc. this actually measures it with a small I2C light sensor. Check out the guide I wrote on it for Adafruit's learning system to see the details:
http://learn.adafruit.com/automatic-monitor-color-temperatur... You can also find the code here:
https://github.com/tdicola/AutoColorTemp