The strontium ruthenates of the Ruddlesden-Popper series have attracted much interest in the last two decades due to the variety of their different ground states. These states, ranging from unconventional superconductivity over metamagnetic behavior with a new low-temperature phase to itinerant ferromagnetism, are often in close competition and thus crucially depend on system parameters and crystal purity. The discussion in this work concentrates on selected exotic phenomena in the ruthenates which are explored within different theoretical frameworks. In a first part, it is shown how the...