Sean Harrison has built a very cool hard drive project. Similar to the Hard Drive Oscilloscope but uses two hard drive voice coils instead of just one. This allows the unit to draw an X/Y image without needing to control one axis by hand.
Similar to the Hard Drive Laser Oscilloscope, But this project uses two hard drives, to project the laser in both the X and Y Axis, Making Funky Laser FX Which move to you music collection. (Pictures and Videos After Link) All You need is a couple of dead hard drives, A Laser Pen few bits of wire, 2 bits of mirror and loads of hot glue!”