Spectral Atlas - Contains a sample of the standard spectral type stars, peculiar stars, variable stars, and some special stars.
SPECTRUM: A Stellar Spectral Synthesis Program - Written by Richard O. Gray of the Department of Physics and Astronomy, Appalachian State University for both research and education in astronomy.
Stellar Spectra - Walks trough the formation of stellar spectra, the genesis of emission lines and absorption lines, and spectral and luminosity classes.