For a long time spin clusters served essentially as model systems for the better understanding of properties of conventional extended magnets. The discovery of intriguing magnetic properties (magnetic hysteresis and quantum tunnelling of the magnetization) 15 years ago completely changed the focus of research. The fascinating field of Single-Molecule Magnets was launched. Are these materials going to be used in high-density data storage devices, could they be building blocks for quantum computers? In this cross-disciplinary area of research chemists, physicists and material scientists work hand in hand in the design and synthesis of new materials and the analysis and understanding of their truly unique physical properties.