In this review we summarize some experimental investigations on the interactions between charged amphiphilic molecules and oppositely charged polyelectrolytes. We first present results on the formation, in bulk solutions, of polyelectrolyte/surfactant complexes of micrometric size. We show how the sample preparation procedure may affect the morphology of the complexes formed and how the kinetics influences the dynamics of their formation. The second and third parts are devoted to two-dimensional systems, namely a lipid bilayer attached to a polyelectrolyte multilayer cushion, on the one hand, and a lipid monolayer at the interface between air and a polyelectrolyte solution, on the other hand. We first demonstrate that, for lipids coupled to polyelectrolyte multilayers, the dynamics of the lipid is completely dominated by the electrostatic interactions with the polymer cushion. We finally investigate, by a combination of several techniques, how the interactions with a polyelectrolyte modify the properties of lipid monolayers and how ordering in an adsorption layer appears.