OperadiO.com
Seven live radio channels on the internet of the best opera and classical music.
http://www.operadio.com

Opera Reviews @ musicOMH.com
Opera reviews from the Royal Opera House, The Coliseum and Glyndebourne.
http://www.musicomh.com/opera/index.htm

MetManiac
Metropolitan Opera broadcasts database including a complete radio/television program list, message board, features, and schedules for future seasons.
http://www.metmaniac.com/

Opera Japonica
Coverage of opera in Japan; includes monthly schedules, reviews, interviews, international reports, and multimedia files.
http://www.operajaponica.org/

OperaGlass
Includes libretti, source texts, performance histories, synopses and discographies plus pictures and background information. Extensive links to composers, librettists, operas, opera companies and opera people. From Stanford University.
http://opera.stanford.edu/

Suite101: Opera
Articles, links and discussions about opera.
http://www.suite101.com/welcome.cfm/opera

Opera-L
Details of the Opera-L mailing list and how to subscribe, plus photos, files and links.
http://www.opera-l.org/

Operas and Composers: A Pronunciation Guide
AIFF format sound clips of names of operas and composers being spoken.
http://patriciagray.net/Operahtmls/works.html

Culturevulture.net - Opera
Opera reviews, graphics, schedules, links.
http://www.culturevulture.net/Opera/OperaIndex.htm

SoYouWanna: Learn About Opera?
One-page introduction to opera for the novice, with explanations of its history, performers, and classic works.
http://www.soyouwanna.com/site/syws/opera/opera.html

Operissimo
Searchable database of performers, composers, compositions, and opera houses.
http://www.operissimo.com/

The Royal Opera: Opera Synopses
On ongoing collection, starting with the 2001/2002 season in London, UK.
http://info.royaloperahouse.org/synopses/

ChevronTexaco Opera Information Center
Developed by the Metropolitan Opera Guild. Includes radio broadcasts, station finder, broadcast news, and an archive in English, Spanish, French, and Portuguese with composer and background information, sound clips, and teaching materials.
http://www.operainfo.org/

Learn
Educational program of the Arizona Opera includes synopses, biographies, and external links, pronunciation guide, terminology, FAQs, surtitles, lecture series, and Opera for Kids. Internal resources include MP3 audio, MOV video, and PDF study guides.
http://www.azopera.com/learn.php

The Aria Database
A searchable database of arias, each includes vocal part and contextual information. Some have sound files and translations.
http://www.aria-database.com/

OperaTalent
Information about opera and people in the industry, from singers to stage managers. Covers auditions, events, broadcasting and in-depth reviews, articles and interviews.
http://www.operatalent.com/