This book comprises three different types of unconventional correlated systems. The first part of this work addresses the open shell alkali sesquioxides. In contrast to theoretical predictions, which suggested half-metallic ferromagnetism for rubidium sesquioxide, dominating antiferromagnetic interactions were found in the experiments. A symmetry reduction and strong electronic correlations of this highly molecular could explain the peculiarities of this system. The second part is about intermetallic Heusler superconductors. All of these were rationally designed using the van Hove scenario as a working recipe. The compounds escape the high density of states at the Fermi energy through a transition into the correlated superconducting state. A highly spin-polarized ferrimagnet with a major technological relevance in the field of spin torque transfer applications completes the unconventional correlated systems in this book.