I know it sounds impossible, but I've tried it myself, and this is real - a christmas tree - in i _makes_stuff's home - that has controls for the lights, inside Minecraft! How it works is pretty simple: log into theserver.fluctis.com, and start playing with switches. An in-game tree gives you some visual feedback, but the real treat seeing the real-life tree change colors!
At the top of this webpage, you will see an image of a tree with an LED rope around it. Play with some of the switches in-game, and you can see the tree in the image change almost instantly, depending on your geographical location. I've been playing with this tree for a little over 20 minutes now, and I still don't get how it works. The creator explains it in the video above, but it almost seems to defy belief. Give it a try yourself, and see!