Other
The Aria Database
The searchable Aria Database features over 1,200 arias from 170 operas by 60 composers. It includes lyrics, translations, synopses of operas, and MIDI files.
Other
Opera Houses and Companies on the Web: 5 Continents
This is list of links to a selection of websites of opera companies. Not all-inclusive, it is large and a good place to begin looking for places that perform opera all over the world.