Plasmonic nanostructures and metamaterials offer the possibility to control and localize light over nanoscopic dimensions. A number of exciting and technologically important applications of such structures have emerged in the past years, including nanoscopic lasers and optical amplifiers, nanoscopic planar photonic systems, and artificial materials with exotic optical properties. Furthermore, the large optical field enhancement associated with plasmonic excitations could enable efficient nonlinear functionality in these optical systems. In this talk, I will discuss our research in some of these directions. In the first part of the talk, I will present our recent work on two-dimensional plasmonic metamaterials for light manipulation, and discuss the potential of this technology for devising flat optical components with polarization-tailored functionality. In the second part, I will present our recent results on the nonlinear optical response of plasmonic nano-films, and of nano-films composed of materials with vanishing electric permittivity. These results indicate that the latter type of materials hold promise for developing metamaterial-based optical devices with efficient nonlinear functionality.