The spontaneous decay of a V-type three-level atom placed in a negative-refractive-index waveguide is analyzed. We find that in thin waveguides, highly efficient surface-guided modes are supported, which do not occur in positive-index waveguides. In addition, at low absorption, the mode density and thus spontaneous emission into particular regular-guided modes is enhanced by several orders of magnitude as compared to regular dielectric waveguides. The asymmetries between emission into the different modes and the enhancement of particular guided modes allow us to induce strong spontaneous emiss...