American Choral Directors Association

Aria Database

CD Sheet Music - many songs and collections available

Choral Public Domain Library

Classical Singer Magazine

Delaware Music Educators Association

Digital Sheet Music

Free Scores

International Music Score Library

Livemocha

Music Minus One - karaoke arias, songs and more

Music Teachers National Association

National Association of Teachers of Singing (NATS)

New York Public Library Internet Archive for Sheet Music

NPR's Series, "50 Great Voices"

Sheet Music Plus - musical theater, pop, opera, classical

Sheetzbox Free Piano Music

The Lied, Art Song and Choral Texts Archive

The National Association for Music Education

The Sheet Music Archive

Vocalist.Org - International Singers Discussion

YoungArts