This review describes advances made in three areas of molecular magnetic materials of the types A: extended frameworks (coordination polymers) showing long-range magnetic order, B: spin-coupled clusters with emphasis on single molecule magnets and (n × n) grid species, C: polynuclear spin-switching (spin crossover) compounds of Fe^II with emphasis on dinuclear compounds and one-dimensional (1D) and three-dimensional (3D) (framework) materials, including porous ‘hybrid’ systems. The work of the author and his group is largely used to provide examples, together with results from other groups and collaborators that are included for comparison and completeness. Supramolecular aspects such as cluster–cluster and chain–chain interactions are discussed where relevant. A brief discussion is also given of the recent studies, carried out elsewhere, dealing with aspects of spintronics and the possible future relevance to molecular computers (type B materials) and with memory and other device possibilities (type C materials)