  Ultra-cold atomic systems provide a new setting where to investigate the role
of long-range interactions. In this paper we will review the basics features of
those physical systems, in particular focusing on the case of Chromium atoms.
  On the experimental side, we report on the observation of dipolar effects in
the expansion dynamics of a Chromium Bose-Einstein condensate. By using a
Feshbach resonance, the scattering length characterising the contact
interaction can be strongly reduced, thus increasing the relative effect of the
dipole-dipole interaction. Such experiments make Chromium atoms the strongest
candidates at present for the achievement of the strong dipolar regime.
  On the theoretical side, we investigate the behaviour of ultra-cold dipolar
systems in the presence of a periodic potential. We discuss how to realise this
situation experimentally and we characterise the system in terms of its quantum
phases and metastable states, discussing in detail the differences with respect
to the case of zero-range interactions.
