This microreview aims at presenting a personal perspective on the possible contributions of molecular metal carbonyl clusters (MCCs) to a better understanding and development of metal nanoparticles. High-nuclearity molecular MCCs are perfectly (atomically) monodisperse, ligand-stabilised metal nanoparticles with nanometric dimensions. Thus, when the nuclearity of molecular clusters is increased and the dimensions of metal nanoparticles are reduced, these two worlds begin to overlap. Herein, the synthesis of larger MCCs is briefly outlined, together with the description of their structural features and physical properties. The use of molecular MCCs as nanometric or subnanometric building blocks for self-assembly of functional nanomaterials is also reported. Finally, the employment of MCCs as precursors for metal nanoparticles after decomposition of the molecular precursor is described. The purpose of this microreview is to discuss some representative examples of all these topics, showing that one of the most promising and fascinating aspects of molecular MCCs is their borderline nature between molecular chemistry and nanochemistry.