Nanosized molecular magnetic materials such as single-molecule magnets and single-chain magnets are recent attractive research targets in the fields of materials chemistry and physics, not only because of their fundamental fascination, but also because of their potential applications as ultimate memory devices or in quantum computations. In this paper, we give our personal perspectives on these materials. In particular "magnetic assemblies of single-molecule magnets", in which inter-molecular interaction is an essential factor in determining their properties, will be focused on together with related compounds reported recently.