The adiabatic motion of ultra-cold, multi-level atoms in spatially varying
laser fields creating a dark state can give rise to effective gauge
potentials. These potentials lead to effective magnetic
fields if the light fields possess a relative orbital angular momentum.
This allows to study quantum-Hall like effects in ultra-cold atomic gases
in various geometries. If the atom-light interaction creates several
degenerate adiabatic eigenstates, the associated gauge potentials are
non-Abelian. A pair of such degenerate dark states emerges e.g. if laser
fields couple three internal states of an atom to a fourth common one
under pairwise two--photon-resonance conditions. For this so-called tripod
scheme we derive general conditions for truly non-Abelian gauge potentials
and discuss special examples. In particular we show that using orthogonal
laser beams with orbital angular momentum an effective magnetic field can
be generated that has a monopole component.