In this project, Arduino is connected to a Processing sketch. The sketch shows the inside of Iron Man's helmet, his HUD (heads up display). A sonar sensor on a servo detects whether enemies are close by and depending on the distance the sketch acts differently.  Check out to video to see it working.
(Images for the processing sketch were used from this Iron Man HUD tutorial)

I also used the sonar sensor to map out the room while it was placed on the servo. The images below represent that. The length of the line is defined by the distance and the placement on the X-axis is defined by the angle of the servo.