Soft matter systems have been investigated by Monte Carlo and Brownian Dynamics simulations. In particular the behaviour of two dimensional binary hard disk mixtures in external periodic potentials has been studied as well as the transport of colloids in micro-channels and the features of proteins in lipid bilayers. Ni nanocontacts have been analyzed by Molecular Dynamics simulations with respect to their conductance and structural properties under stretching, and the effect of temperature, composition and system size on the structural properties of Ni x Fe1 −x alloys has been studied. The properties of Si clusters in external fields have been computed by density functional methods, and the static and dynamic properties of model magnetic systems by the Landau-Lifshitz-Gilbert equation. In the next sections we give an overview on our recent results.