  We review explicit solutions to the stationary axisymmetric Einstein-Maxwell
equations which can be interpreted as disks of charged dust. The disks of
finite or infinite extension are infinitesimally thin and constitute a surface
layer at the boundary of an electro-vacuum. The Einstein-Maxwell equations in
the presence of one Killing vector are obtained by using a projection
formalism. The SU(2,1) invariance of the stationary Einstein-Maxwell equations
can be used to construct solutions for the electro-vacuum from solutions to the
pure vacuum case via a so-called Harrison transformation. It is shown that the
corresponding solutions will always have a non-vanishing total charge and a
gyromagnetic ratio of 2. Since the vacuum and the electro-vacuum equations in
the stationary axisymmetric case are completely integrable, large classes of
solutions can be constructed with techniques from the theory of solitons. The
richest class of physically interesting solutions to the pure vacuum case due
to Korotkin is given in terms of hyperelliptic theta functions. The Harrison
transformed hyperelliptic solutions are discussed.
