Has anybody tried doing this kind of project where arduino is used to control the lights for the room?
LEDs are probably the best form of low voltage lighting. They are not quite mainstream yet, so there’s still a lot of hacker space. But you can build a pretty good setup with the knowledge available in these forums. You could easily do this for a room. The picture below is of my bike LED headlight working in bright daylight.
The project is powered from a single 12V DC source for the LEDs and the Arduino. It’s 24 watts of LED light and is as bright or brighter than the 125 watts or so of lamps I have in that room.
If all you wanted to do was light a room, you probably wouldn’t need an Arduino. But if you wanted to do something fun and/or intelligent based on outside light or motion or something, then sure an Arduino is your solution.