NATS The National Association of Teachers of Singing is a great place to network and learn more about the singing voice.
All about choirs Choral Net is a good resource for singers looking for a choir to join, helpful tips, job openings, and discussion groups.
A great place to get sheet music for voice here Buy music
Theatre Alliance of Philadelphia check the job opportunities for auditions in the Greater Philadelphia area. It is also a good resource for knowing what is happening at all the local theaters.
Classical Singer is a good resource about performing, careers, discussions, practical advice, and more!
Texts of songs in all languages, with translations.
Anything you need to know about Opera Arias
To work on Theory Skills
Learn more about the History of Opera