God is peace, beyond all tumult and shouting. Our hymns, accordingly, ought to be angelic, without tumult . . . Psalmody has been given us that we may rise from the sensory to the intelligible and true. —St. Gregory of Sinai
Christ is risen!
I’m putting together a list of sources for Orthodox/Eastern Rite sheet music. This is rather a pain, because 1) we have so many musical traditions, and 2) there is nothing where you can get anything you might need. However, there are sites that post pdf files of sheet music, and as I collect more, I’ll add them here.
If you’re interested in Byzantine, this is where you start: Father Ephraim’s Byzantine Music Formulae. Hat tip to Basil Crow, who has a very good Byzantine music page. Also, check out these Byzantine Chant Tutorials (PDF and example MP3 files).
St Seraphim Orthodox Cathedral choir page, OCA, mostly Slavic SATB. Link.
OCA Slavic liturgical music, arranged by liturgical season, etc. Excellent. Link.
OCA Liturgical Music page, mostly Slavic SATB. Link.
Antiochian Orthodox Sacred Music page, quite a compendium of music. Lots of Byzantine (traditional and harmonized), as well as Syrian Byzantine, and a good amount of Slavic SATB. Link.
St Michael’s Greek Catholic Church (Byzantine Catholic, Rusyn), a huge compendium of music, much of it in Slavonic, but lots in English, lots of Prostopinije (Carpatho-Russian) music. Link.
St Tikhon’s Monastery Two Part Chant page. Link.
Podoben, Slavic music in both English and Slavonic. Link.
Theologian.Org Byzantine Chant page. Link.
St Anthony’s Monastery, Divine Music Project. Link.
Holy Cross Kliros. Very good Znamenny music library. Link.
Monastery of St John music page. Mixed Slavic, lots of Znamenny and some Byzantine. Link.
Choir resources thread on OrthodoxChristianity.Net: Link.
Chanter resources thread on OrthodoxChristianity.Net: Link.
For Galician chant, see here.
Russian (Obikhod) and Kievan tones (sound files) on OrthodoxWiki
PSALOM Eastern Orthodox Chant Documentation Project, a wealth of information
Byzantine Ruthenian Liturgical Chant, a Prostopinije resource
Finally, my suggestions for Western choirs/chanters looking for material.