  It is widely known that cosmic magnetic fields, i.e. the fields of planets,
stars, and galaxies, are produced by the hydromagnetic dynamo effect in moving
electrically conducting fluids. It is less well known that cosmic magnetic
fields play also an active role in cosmic structure formation by enabling
outward transport of angular momentum in accretion disks via the
magnetorotational instability (MRI). Considerable theoretical and computational
progress has been made in understanding both processes. In addition to this,
the last ten years have seen tremendous efforts in studying both effects in
liquid metal experiments. In 1999, magnetic field self-excitation was observed
in the large scale liquid sodium facilities in Riga and Karlsruhe. Recently,
self-excitation was also obtained in the French "von Karman sodium" (VKS)
experiment. An MRI-like mode was found on the background of a turbulent
spherical Couette flow at the University of Maryland. Evidence for MRI as the
first instability of an hydrodynamically stable flow was obtained in the
"Potsdam Rossendorf Magnetic Instability Experiment" (PROMISE). In this review,
the history of dynamo and MRI related experiments is delineated, and some
directions of future work are discussed.
