The Aria Database ( http://www.aria-database.com ) Diverse collection of information on over 1000 operatic arias. Database includes translations and aria texts of most arias as well as a collection of MIDI files of operatic arias and ensembles.
The Metropolitan Opera. New York, NY (http://www.metopera.org/)
Operabase ( http://operabase.com/index.cgi?lang=en ) Very extensive web site featuring news, reviews, artists, etc.
OperaGlass ( http://opera.stanford.edu/main.html ) Stanford University site with detailed information on various aspects of opera, including composers, libretti, synopses, etc.
University of California, Berkeley. Music Library (http://www.lib.berkeley.edu/MUSI/)
Worldwide Internet Music Resources (http://www.music.indiana.edu/music_resources/) One of the finest, most well organized collections of music sites available, from the largest music school in the world.