This is a project I created for a Digital Art and Installations class, but I gave it to my little brother for Christmas. The class covered basics of several types of programming, and our projects were meant to be an interactive cross between art and technology. This was a fun and easy project with really impressive results (if I do say so my self). The same technology could be applied to many different types of types of projects. The technology is very easily altered as well, for example, I was considering using a distance sensor or a light sensor. I had everything on hand, so it cost nothing.
It does several different weather functions, and each color light is also individuality controllable, to create any combination.
Sorry the photos don't really do it justice! Check out the video to see it in action:
How To and more photos here: http://www.instructables.com/id/IR-Remote-Controlled-Color-Changing-Cloud-Arduino/