The growing interest in the self-assembly of nanoparticles is guided by the vast application potential of assembled structures. Broadly, bottom-up construction starting at the nanoscale and using functional nanoparticles can result in complex structures that cannot be obtained with traditional top-down approaches. For instance, the fabrication of thin films of ordered bi-functional core-shell nanoparticles are only possible with a self-assembly process. In fact, otherwise sophisticated thin-film techniques can also be replaced by self-assembly based techniques for certain applications. For an overview, Figure outlines the known applications of nanoparticle clusters and films. With the multitude of interesting emerging applications, only a broad topical selection is provided here. In the following, interesting applications where self-assembled structures play a significant role are discussed in detail.