Sun Microsystems filed a patent for a heatsink design with magneto-hydrodynamic technology in a closed fluid system. This technology will circulate a liquid through the heatsink without any mechanical pumping.
Just like the drive system used on the Russian submarine Red October in the movie "The Hunt for Red October," this type of magneto-hydrodynamic, or "caterpillar," is designed to use micro-magnetic fields to squeeze internal bladders which in turn create a pumping action. While the end result is a real movement of liquid there are no moving parts to this design. The bladder is squeezed remotely by magnetic fields and is, therefore, almost completely silent.
The purpose of the liquid is to take the heat away from the source and move it up very quickly to its larger surface area which can then expel the heat via metal/air surfaces just like traditional heatsinks. The interesting part of this design, however, is the use of caterpillar pumping action coupled with a closed liquid system.