Ferrofluid fun! 
Ferrofluid is a liquid which becomes magnetized in the presence of a magnetic field. It has many practical uses, but I'm mostly interested in how cool it looks! Anytime you expose the fluid to a strong magnet, or magnet material, it creates a very interesting shape/structure. Moving the magnetic source around the liquid causes its molecules to cluster, or diffuse. It is a rather cool sci-fi style effect.
I'm using a small amount of ferrofluid, contained within a glass vial. Small neodymium "rare earth magnets" are the magnetic source. In some cases, I've inserted a steel ball or screw, so the fluid has more volume and creates different shapes. All in all, this is just a fascinating little scientific sculpture to have around and share with others!
Safety tip: Neodymium magnets can be dangerous, and even more dangerous when used with glass. Extreme caution should be used to avoid serious injury.
Wikipedia:
http://en.wikipedia.org/wiki/Ferrofluid
Ferrofluid:
http://www.amazingmagnets.com/
K&J Magnetics:
http://www.kjmagnetics.com
Discount Vials:
http://www.discountvials.com
Feb 17th 2011 