  Recently, the issue of the role of the Eddington limit in accretion discs
became a matter of debate. While the classical (spherical) Eddington limit is
certainly an over-simplification, it is not really clear how to treat it in a
flattened structure like an accretion disc. We calculate the critical accretion
rates and resulting disc luminosities for various disc models corresponding to
the classical Eddington limit by equating the attractive and repulsive forces
locally. We also discuss the observational appearance of such highly accreting
systems by analyzing their spectral energy distributions. Our calculations
indicate that the allowed mass accretion rates differ considerably from what
one expects by applying the Eddington limit in its classical form, while the
luminosities only weakly exceed their classical equivalent. Depending on the
orientation of the disc relative to the observer, mild relativistic beaming
turns out to have an important influence on the disc spectra. Thus, possible
super-Eddington accretion, combined with mild relativistic beaming, supports
the idea that ultraluminous X-ray sources host stellar mass black holes and
accounts partially for the observed high temperatures of these objects.
