I will give an overview of coupled dark energy models, in which dark energy interacts with other species in the universe. I will illustrate the effects that coupled dark energy and the presence of a fifth force can have at the linear and non-linear level on structure formation. In particular I will describe the case of growing neutrino quintessence, where dark energy properties are connected to the neutrino mass, predicting the possibility of having stable neutrino lumps at supercluster scales.