Not looking too far into the stacks - where the gregorian chants play.
Allegri Miserere by The Tallis Scholars (Palestrina, and so on)
Venetian Vespers by Gabrieli & Consort Players
Officium by The Hilliard Ensemble
Dalla Terra Mina (Sony) - I don't remember this one
Well, that's enough. I might have to listen to these myself again.