The most obvious extragalactic targets for optical/infrared interferometers are Active Galactic Nuclei. In this document, I try to overview other topics that could be of interest to studies of galaxies and whether they could be adequate for a next generation interferometer. The very high spatial resolution would be profitable for extragalactic supernovae, globular clusters, star forming regions, gravitational lenses and some stellar studies in very close galaxies. However, sensitivity is the main concern since the interesting magnitude limit would have to be of the order of 25 or more for these studies not to remain marginal.