Summary: Competition of energies gives rise to interesting phenomena; in recent years, nonlocal energies were introduce to model long-range interaction effects. Starting from some relevant everyday examples, two kinds of nonlocal models are treated, one related to the Laplace and the other to the Helmholtz operator, showing some recent and new results concerning stable periodic minimal configurations. The concept of stability is crucial for the (possibly numerical) approximation of the Gamma-limit solution by solutions of the original problems.