The pulse-laser pumped emission from a dye-doped polymer film, as it is coated on a thick Ag-island film of large pseudotabular nanoparticles, is strongly affected by the metal-enhanced fluorescence very near the Ag-island, so as to produce an avalanche of stimulated emission with a bandwidth as small as 2.5nm. A modified system with a gain region laterally extended outside the Ag-island film gave rise to an even narrower emission from the film edges, down to 1.5nm in bandwidth. Furthermore, it was found that mixing of several different laser dyes in the polymer film, with significant overlaps of the fluorescence and absorption spectra, caused still stronger and narrower emission, sometimes 0.65nm in bandwidth, at some controlled positions in the visible region, while the excitation (pump) wavelength was fixed at e.g., 532nm.