I love how, at the beginning of this video, developer Jim Rutherford says, "This is just a little weekend hacking project we through together." How modest!
Rutherford's son is ten, and loves Minecraft. Dad decided to mess around with a Phillips Vue lightbulb, and connect it to an app running on his iPad that then connects to the Minecraft server and changes color and brightness in sync with the Minecraft day/night cycle. The app lets them set the time of day, debug the cycle, and even scrub through it, assumedly issuing server commands to achieve the effects.
Not only is this super cool, and would make my own 10-year-old son squeal with joy, but Rutherford has put the code up on github, a repository of open source code that anyone can access. If you're a hacker/developer, be sure to head on over there and grab the code.