  In this paper we highlight the advantages of using point-contact spectroscopy
(PCS) in multigap superconductors like MgB_2, both as a fundamental research
tool and as a non-destructive diagnostic technique for the optimization of
thin-film characteristics. We first present some results of crucial fundamental
interest obtained by directional PCS in MgB_2 single crystals, for example the
temperature dependence of the gaps and of the critical fields and the effect of
a magnetic field on the gap amplitudes. Then, we show how PCS can provide
useful information about the surface properties of MgB_2 thin films (e.g. Tc,
gap amplitude(s), clean or dirty-limit conditions) in view of their
optimization for the fabrication of tunnel and Josephson junctions for
applications in superconducting electronics.
