A comprehensive review of spin-polarized Auger-electron spectroscopy on 3d transition-metal ferromagnets is presented. The kind of information obtained from the Auger-electron spin polarization depends on the particular transition involved. Decays with emission of a valence electron probe the local magnetization at the site where the transition occurs. Particularly, the super-Coster-Kronig ${M}_{23}$${M}_{45}$${M}_{45}$ transitions are well suited for monitoring magnetic behavior with elemental resolution. Details of the spectra are sensitive to screening and electron correlation effects as illustrated by a comparison between Fe and Ni. Furthermore, core-hole-only decays\char22{}as exemplified by the ${L}_{3}$${M}_{23}$${M}_{23}$ process\char22{}yield exchange-interaction strengths between partly filled shells on a single atom.