Opera Magazines 
OperaOpera Interesting articles on Opera by Paolo Del Lungo (English & Italian)
MP3-Midi Files
Karadar Big section for MP3 & another for Midi
Ficheros de Música Clásica - R. Pajares Box
Freeware Software
Winamp.com One of the best players for MP3, Midi, wav Opera files
LyricsAMP. Winamp Component A freeware component of WINAMP so that you can read lyrics while listening to music with WINAMP
Kazaa Media Desktop One of the most populars peer-to-peer software to exchange your MP3 files and more
Emule-Project.net Another popular software for exchanging files
Books
Amadeus Press publishes a full line of books on classical music and opera
