Specular reflectometry of polarized-neutrons was developed in the 1980s as a tool for measuring magnetic depth profiles in flat films, which were laterally uniform. When the lateral uniformity breaks down in an assembly of domains, off-specular grazing incidence scattering takes place. This review discusses this new frontier of reflectometry, describing the advances that are taking place in linking the observations of the scattering at grazing incidence with the size, the statistics, and the magnetic orientation of the domains. The article discusses also the progress made in linking the domain distribution thus found with the transport properties of these nanomagnetic systems.