Spiral Brain (who was a recent contest winner) has made an interesting Spinning Mirror Laser Project. At first when I watched the video the beginning looked like someone was spinning a few bright LEDs in their hands on a dark night. The patterns that followed show off the capability of the system to make some nice looking complex pattens.
“The main hardware setup consists of a Laser and two motors. A mirror is attached to each motor in a way that the mirror is slightly tilted to the axis of the motor. when the motor rotates the mirror the plane of the mirror is not flat and projects the laser in the form of circles. each motor creates a circle from the light falling on it. this combines to create circles within circles thus creating the effect. to add to the effect the laser light is pulsed using PWM which breaks the circle into lines further enhancing it.”