The magnetic top shown by George Green is spinning because of following reason:
The missing magnet in the outer ring creates an ex-centered potential well in the magnetic potential energy, this potential well creates a magnetic force applied to the magnetic top; as the top is drifting to the center of that well it is submitted to a torque aligning its axis to the external magnetic field and a no-slip frictional force at the contact point between the ball and the table, the non alignment of this frictional force and the magnetic force create a torque causing the spinning of the ball...
All this can be put into equations and simulated; you can check the simulations (movies) and the paper at
http://www.acm.caltech.edu/~owhadi/BallisticTransport/
You can also check experimentally that friction is the caused of the rotation by trying the experiment on a slippery surface (ice...)
So the system is actually not "creating" energy but dissipating the energy introduced by the motion of the outer ring through friction...
This being said some funky things (no "energy creation") happen if you add noise to the system
Houman