Flying frogs and levitating magnets with your hand

With all the assignments/speeches we have to sort through at the moment I though this would be a pleasant diversion on a Monday morning:

http://www.physics.ucla.edu/marty/diamag/diajap00.pdf

The paper is based on Earnshaw's theorem, which proves that there exists no stable equilibriums for 1/r^2 forces. In the simplest context, it explains why no matter how hard you try you've never been able to balance two magnets with their opposing poles as a kid.

The paper discusses how pre-WW2 it was shown by Braunbeck that it was possible to achieve stable equilibria with diamagnetic materials (hence why superconductors can levitate). They apply some of his basic theory to some very interesting examples, i.e. finding the stable equilibrium point to levitate a frog in mid-air. This is accomplished due to the dia-magnetic nature of many molecules, such as water and proteins. They even show how the minute diamagnetic nature of your fingers (and apparently a book on the Feynmann lectures) can be used to stabilise the equilibrium point of a small magnet in a field.