When Helium is cooled to 2 degree above absolute zero, a dramatic transformation takes place. Helium, which usually can be seen as a bubbling, rapidly evaporating substance, becomes stable and starts looking a bit like water. This liquid, called superfluid helium, will leak through a glass surface when poured on it. Here’s a short video demonstrating the phenomenon. Enjoy!
Edit 16/12/07: Ok Bad headline, sorry about that folks, and thanks to DougBTX on reddit for the correction. The bottom of the beaker is composed of ceramic, which has very tiny holes in it. Since superfluid helium has zero viscosity, it can easily flow through these tiny holes.