The effect of nanoparticles in the spontaneous emission from a nearby atom is studied by calculating the emission probability and the distribution of the near field for various nanoparticle shapes and positions of the atom. For atoms near a gold sphere or in the region between two neighbouring spheres, a strong enhancement of the emission takes place for transition energies near the plasmon resonances of the system. Finally, the near field associated to the emission is examined when the atom is located at the focus of a dielectric ellipsoid, in which case a strong enhancement of the field at the other focus is observed at certain resonance energies, even when the dimension of the ellipsoid is comparable to the wavelength. This work has been supported in part by the Basque Departamento de Educación, Universidades e Investigación, the University of the Basque Country UPV/EHU (Contract No. 00206.215-13639/2001), and the Spanish Ministerio de Ciencia y Tecnología (Contract No. MAT2001-0946). Peer reviewed