Clusters and nanoparticles often have properties rather different to those of the corresponding bulk material, which is due to their large surface-to-volume ratio and in general to quantum size effects, the discretization of otherwise continuous densities of states. Especially the latter makes them highly interesting candidates for the study of few to many particle physics. In my talk I will first explain the intricate interplay between electronic and geometric structure in simple metal clusters, which has been clarified by a combination of photoelectron spectroscopy on free, size-selected alkali and noble metal clusters and DFT-calculations. I will discuss a couple of examples in detail – among them a newly identified chiral tetrahedral structure of sodium clusters, which rivals the otherwise ubiquitous icosahedral packing motif, and somewhat exotic structures of gold clusters, which are due to the special bonding properties of gold. I will then discuss dynamical processes, in particular the role of many-particle dynamics in the photoionization of simple metal clusters, which have been studied using angle-resolved photoelectron spectroscopy. The angular distributions can be described very well by a simple model assuming the electrons to freely rotate inside large spherical box potentials. Surprisingly it is valid down to very small sizes – even the photoemission from Cu5- clusters is in agreement with the model, although this cluster is small and far from spherical. For this cluster also a counterintuitive dependence of the photoelectron angular distributions on the final vibrational state of the cluster was observed, hinting at photoemission via autoionizing excited states of the anion. I will finish by discussing a more complex system, Nb clusters, which exhibit a couple of unusual properties that may or may not be related to the superconductivity seen in the bulk material.