Resources for Singers: 

Angel Diva Music 
Jan Linder-Koda is an award winning singer-songwriter, producer, actress, and artist developer based out of LA.  I LOVE her and her philosophy and performance techniques.  She has some fantastic resources on her site, especially her book "Once More with Feeling" and the accompanying DVD.  Check it out. 
http://www.angeldivamusic.com/Products_ArtistDevelopmentGuide.php