Au and Ag nanoparticles have optical properties that have made them useful as tags in a wide variety of measurement schemes. This Progress Report discusses several different schemes in which Au and Ag nanoparticles have been used as surface-enhanced Raman scattering (SERS) tags for the measurement of biomolecules. As an example application, results using glass-coated nanotags (Nanoplex Biotags) in, a lateral flow immunoassay kit are presented.