Magic Fluid Control
By N. Thuerey, R. Keiser, M. Pauly, U. Ruede

This is cool.

More info:

http://www10.informatik.uni-erlangen.de/%7Esinithue/ani_mfc/

and

http://www.blendernation.com/2006/12/13/magic-fluid-control/

This video isn’t my work, I’m just posting it because I think people should check it out.