This is an informal kitchen counter experiment to replicate the ANL "Magnetic Snakes" experiment.  The ANL experiment used 90um nickel spheres floating on water in a beaker placed inside a coil modulated with a low-frequency (<100Hz) sine wave.   For more information about the ANL experiment, see this news clip and this publication.  I replicated the ANL experiment using ferrite powder in place of the nickel spheres.  I designed the experiment so that it can be performed by anyone at home.

In the ANL experiment, the field lines are perpendicular to the water's surface (in contrast to the old "iron filings on paper" demo you did back in the third grade).  The moving snakes and other patterns arise from complex interactions between the vibrating particles floating on the surface, attraction between the magnetized particles, and waves created on the water's surface.   See my writeup below for more speculation.

My personal opinion, after thinking about this experiment, is that much more experimentation is needed to show this research is novel and useful.  I feel ANL needs to do some analysis to show that the results aren't just the combination of other well-understood effects in order to prove novelty.  For example, an expert in field theory might be able to glance at their results and say, "Oh, those lines on the water are just field lines.  I see those all the time."    I also feel that ANL needs to show that the results are not the result of chaotic interactions, as such interactions are inherently unpredictable (the weather is a classic example of a chaotic process).  I feel that ANL has done a poor job of isolating factors, and that more experiments are needed such as: replacing water with oil, ensuring the container is mechanically isolated from external vibration sources, and using composite photos to view patterns.

I doubt it's directly related, but magnetic snakes are suggestive to me of magnetohydrodynamic propulsion  and the related homopolar motor.  These links tell how to do your own demos.

You will find below  instructions on how to do the experiment yourself and a movie of my results showing swimming "magnetic snakes".

ANL Results using Nickel Spheres

Home Results using Ferrite Powder

Writeup describing how to do the experiment at home as well as a discussion of the results:

http://sites.google.com/site/edwardcraighyatt/CraigsProjects/magnetic-snakes/ferritesnakes.doc?attredirects=0

Here is a movie of the experiment performed using ferrite powder:

http://sites.google.com/site/edwardcraighyatt/CraigsProjects/magnetic-snakes/ferritesnakes.wmv?attredirects=0