A long length of wire is suspended horizontally between the poles of a magnetron magnet. When a large current from a 12V storage battery is passed through the wire, the wire jumps out of the magnetic field. When the direction of the current is switched, the wire jumps the opposite direction.

The magnetron magnet in this demonstration was originally used in MIT's groundbreaking research developing radar during and after World War II. Microwave emitting cavity magnetrons need strong magnetic fields, which were often created by powerful permanent magnets like the one used in this demo.
See original video on MIT TechTV - http://techtv.mit.edu/videos/843