Singing from the Lectionary
http://lectionarysong.blogspot.com/

Choral Public Domain Library
Get lost in this free candy store.
http://www.cpdl.org/wiki/index.php/Main_Page

Free-scores
Instrumental, etc.
http://www.free-scores.com/

Petrucci Music Library
http://imslp.org/

Classical scores
http://musopen.com/

Music--not free, but immediate!http://www.handlo-music.com/index.htm