I recently came across a company called Creative Home Engineering that has a website for creating secret rooms in your house. Personally I like the pool table coming up out of the middle of the room animation.

All joking aside I can see a technological application for this. In the hidden room is all the servers and electronic backbones for a smart house. It gives you access to the room using a keypad. That way its not completely obvious to the casual visitor where the computer(s) running the house are located.

Check out the website